Since ancient times, north Zhejiang and neighbouring south Jiangsu have been famed for their prosperity and opulence[citation needed], and simply inserting north Zhejiang place names (Hangzhou, Jiaxing, etc.) into poetry gave an effect of dreaminess, a practice followed by many noted poets. In particular, the fame of Hangzhou (as well as Suzhou in neighbouring Jiangsu province) has led to the popular saying: "Above there is heaven; below there is Suzhou and Hangzhou" (上有天堂，下有苏杭), a saying that continues to be a source of pride for the people of these two still prosperous cities.


The Ministry of Defence (MoD) is the British government department responsible for implementing the defence policy set by Her Majesty's Government, and is the headquarters of the British Armed Forces.


The MoD states that its principal objectives are to defend the United Kingdom of Great Britain and Northern Ireland and its interests and to strengthen international peace and stability. With the collapse of the Soviet Union and the end of the Cold War, the MoD does not foresee any short-term conventional military threat; rather, it has identified weapons of mass destruction, international terrorism, and failed and failing states as the overriding threats to Britain's interests. The MoD also manages day-to-day running of the armed forces, contingency planning and defence procurement.


During the 1920s and 1930s, British civil servants and politicians, looking back at the performance of the state during World War I, concluded that there was a need for greater co-ordination between the three Services that made up the armed forces of the United Kingdom—the British Army, the Royal Navy, and the Royal Air Force. The formation of a united ministry of defence was rejected by David Lloyd George's coalition government in 1921; but the Chiefs of Staff Committee was formed in 1923, for the purposes of inter-Service co-ordination. As rearmament became a concern during the 1930s, Stanley Baldwin created the position of Minister for Coordination of Defence. Lord Chatfield held the post until the fall of Neville Chamberlain's government in 1940; his success was limited by his lack of control over the existing Service departments and his limited political influence.


Winston Churchill, on forming his government in 1940, created the office of Minister of Defence to exercise ministerial control over the Chiefs of Staff Committee and to co-ordinate defence matters. The post was held by the Prime Minister of the day until Clement Attlee's government introduced the Ministry of Defence Act of 1946. The new ministry was headed by a Minister of Defence who possessed a seat in the Cabinet. The three existing service Ministers—the Secretary of State for War, the First Lord of the Admiralty, and the Secretary of State for Air—remained in direct operational control of their respective services, but ceased to attend Cabinet.


From 1946 to 1964 five Departments of State did the work of the modern Ministry of Defence: the Admiralty, the War Office, the Air Ministry, the Ministry of Aviation, and an earlier form of the Ministry of Defence. These departments merged in 1964; the defence functions of the Ministry of Aviation Supply merged into the Ministry of Defence in 1971.


The Ministers and Chiefs of the Defence Staff are supported by a number of civilian, scientific and professional military advisors. The Permanent Under-Secretary of State for Defence (generally known as the Permanent Secretary) is the senior civil servant at the MoD. His or her role is to ensure the MoD operates effectively as a department of the government.


The current Chief of the Defence Staff, the professional head of the British Armed Forces, is General Sir Nicholas Houghton, late Green Howards. He is supported by the Vice Chief of the Defence Staff, by the professional heads of the three services of HM Armed Forces and by the Commander of Joint Forces Command.


There are also three Deputy Chiefs of the Defence Staff with particular remits, Deputy Chief of the Defence Staff (Capability), Deputy CDS (Personnel and Training) and Deputy CDS (Operations). The Surgeon General, represents the Defence Medical Services on the Defence Staff, and is the clinical head of that service.


Additionally, there are a number of Assistant Chiefs of Defence Staff, including the Assistant Chief of the Defence Staff (Reserves and Cadets) and the Defence Services Secretary in the Royal Household of the Sovereign of the United Kingdom, who is also the Assistant Chief of Defence Staff (Personnel).


The 1998 Strategic Defence Review and the 2003 Delivering Security in a Changing World White Paper outlined the following posture for the British Armed Forces:


The MoD has since been regarded as a leader in elaborating the post-Cold War organising concept of "defence diplomacy". As a result of the Strategic Defence and Security Review 2010, Prime Minister David Cameron signed a 50-year treaty with French President Nicolas Sarkozy that would have the two countries co-operate intensively in military matters. The UK is establishing air and naval bases in the Persian Gulf, located in the UAE and Bahrain. A presence in Oman is also being considered.


The Strategic Defence and Security Review 2015 included £178 billion investment in new equipment and capabilities. The review set a defence policy with four primary missions for the Armed Forces:


Following the end of the Cold War, the threat of direct conventional military confrontation with other states has been replaced by terrorism. Sir Richard Dannatt predicted British forces to be involved in combating "predatory non-state actors" for the foreseeable future, in what he called an "era of persistent conflict". He told the Chatham House think tank that the fight against al-Qaeda and other militant Islamist groups was "probably the fight of our generation".


Dannatt criticised a remnant "Cold War mentality", with military expenditures based on retaining a capability against a direct conventional strategic threat; He said currently only 10% of the MoD's equipment programme budget between 2003 and 2018 was to be invested in the "land environment"—at a time when Britain was engaged in land-based wars in Afghanistan and Iraq.


The Defence Committee—Third Report "Defence Equipment 2009" cites an article from the Financial Times website stating that the Chief of Defence Materiel, General Sir Kevin O’Donoghue, had instructed staff within Defence Equipment and Support (DE&S) through an internal memorandum to reprioritize the approvals process to focus on supporting current operations over the next three years; deterrence related programmes; those that reflect defence obligations both contractual or international; and those where production contracts are already signed. The report also cites concerns over potential cuts in the defence science and technology research budget; implications of inappropriate estimation of Defence Inflation within budgetary processes; underfunding in the Equipment Programme; and a general concern over striking the appropriate balance over a short-term focus (Current Operations) and long-term consequences of failure to invest in the delivery of future UK defence capabilities on future combatants and campaigns. The then Secretary of State for Defence, Bob Ainsworth MP, reinforced this reprioritisation of focus on current operations and had not ruled out "major shifts" in defence spending. In the same article the First Sea Lord and Chief of the Naval Staff, Admiral Sir Mark Stanhope, Royal Navy, acknowledged that there was not enough money within the defence budget and it is preparing itself for tough decisions and the potential for cutbacks. According to figures published by the London Evening Standard the defence budget for 2009 is "more than 10% overspent" (figures cannot be verified) and the paper states that this had caused Gordon Brown to say that the defence spending must be cut. The MoD has been investing in IT to cut costs and improve services for its personnel.


The Ministry of Defence is one of the United Kingdom's largest landowners, owning 227,300 hectares of land and foreshore (either freehold or leasehold) at April 2014, which was valued at "about £20 billion". The MoD also has "rights of access" to a further 222,000 hectares. In total, this is about 1.8% of the UK land mass. The total annual cost to support the defence estate is "in excess of £3.3 billion".


The defence estate is divided as training areas & ranges (84.0%), research & development (5.4%), airfields (3.4%), barracks & camps (2.5%), storage & supply depots (1.6%), and other (3.0%). These are largely managed by the Defence Infrastructure Organisation.


The headquarters of the MoD are in Whitehall and are now known as Main Building. This structure is neoclassical in style and was originally built between 1938 and 1959 to designs by Vincent Harris to house the Air Ministry and the Board of Trade. The northern entrance in Horse Guards Avenue is flanked by two monumental statues, Earth and Water, by Charles Wheeler. Opposite stands the Gurkha Monument, sculpted by Philip Jackson and unveiled in 1997 by Queen Elizabeth II. Within it is the Victoria Cross and George Cross Memorial, and nearby are memorials to the Fleet Air Arm and RAF (to its east, facing the riverside). A major refurbishment of the building was completed under a PFI contract by Skanska in 2004.


Henry VIII's wine cellar at the Palace of Whitehall, built in 1514–1516 for Cardinal Wolsey, is in the basement of Main Building, and is used for entertainment. The entire vaulted brick structure of the cellar was encased in steel and concrete and relocated nine feet to the west and nearly 19 feet (5.8 m) deeper in 1949, when construction was resumed at the site after World War II. This was carried out without any significant damage to the structure.


The most notable fraud conviction was that of Gordon Foxley, head of defence procurement at the Ministry of Defence from 1981 to 1984. Police claimed he received at least £3.5m in total in corrupt payments, such as substantial bribes from overseas arms contractors aiming to influence the allocation of contracts.


A government report covered by the Guardian in 2002 indicates that between 1940 and 1979, the Ministry of Defence "turned large parts of the country into a giant laboratory to conduct a series of secret germ warfare tests on the public" and many of these tests "involved releasing potentially dangerous chemicals and micro-organisms over vast swaths of the population without the public being told." The Ministry of Defence claims that these trials were to simulate germ warfare and that the tests were harmless. Still, families who have been in the area of many of the tests are experiencing children with birth defects and physical and mental handicaps and many are asking for a public inquiry. According to the report these tests affected estimated millions of people including one period between 1961 and 1968 where "more than a million people along the south coast of England, from Torquay to the New Forest, were exposed to bacteria including e.coli and bacillus globigii, which mimics anthrax." Two scientists commissioned by the Ministry of Defence stated that these trials posed no risk to the public. This was confirmed by Sue Ellison, a representative of Porton Down who said that the results from these trials "will save lives, should the country or our forces face an attack by chemical and biological weapons." Asked whether such tests are still being carried out, she said: "It is not our policy to discuss ongoing research." It is unknown whether or not the harmlessness of the trials was known at the time of their occurrence.


The MoD has been criticised for an ongoing fiasco, having spent £240m on eight Chinook HC3 helicopters which only started to enter service in 2010, years after they were ordered in 1995 and delivered in 2001. A National Audit Office report reveals that the helicopters have been stored in air conditioned hangars in Britain since their 2001[why?] delivery, while troops in Afghanistan have been forced to rely on helicopters which are flying with safety faults. By the time the Chinooks are airworthy, the total cost of the project could be as much as £500m.


In April 2008, a £90m contract was signed with Boeing for a "quick fix" solution, so they can fly by 2010: QinetiQ will downgrade the Chinooks—stripping out some of their more advanced equipment.


In October 2009, the MoD was heavily criticized for withdrawing the bi-annual non-operational training £20m budget for the volunteer Territorial Army (TA), ending all non-operational training for 6 months until April 2010. The government eventually backed down and restored the funding. The TA provides a small percentage of the UK's operational troops. Its members train on weekly evenings and monthly weekends, as well as two-week exercises generally annually and occasionally bi-annually for troops doing other courses. The cuts would have meant a significant loss of personnel and would have had adverse effects on recruitment.


In 2013 it was found that the Ministry of Defence had overspent on its equipment budget by £6.5bn on orders that could take up to 39 years to fulfil. The Ministry of Defence has been criticised in the past for poor management and financial control, investing in projects that have taken up to 10 and even as much as 15 years to be delivered.


The term high definition once described a series of television systems originating from August 1936; however, these systems were only high definition when compared to earlier systems that were based on mechanical systems with as few as 30 lines of resolution. The ongoing competition between companies and nations to create true "HDTV" spanned the entire 20th century, as each new system became more HD than the last.In the beginning of the 21st century, this race has continued with 4k, 5k and current 8K systems.


The British high-definition TV service started trials in August 1936 and a regular service on 2 November 1936 using both the (mechanical) Baird 240 line sequential scan (later to be inaccurately rechristened 'progressive') and the (electronic) Marconi-EMI 405 line interlaced systems. The Baird system was discontinued in February 1937. In 1938 France followed with their own 441-line system, variants of which were also used by a number of other countries. The US NTSC 525-line system joined in 1941. In 1949 France introduced an even higher-resolution standard at 819 lines, a system that should have been high definition even by today's standards, but was monochrome only and the technical limitations of the time prevented it from achieving the definition of which it should have been capable. All of these systems used interlacing and a 4:3 aspect ratio except the 240-line system which was progressive (actually described at the time by the technically correct term "sequential") and the 405-line system which started as 5:4 and later changed to 4:3. The 405-line system adopted the (at that time) revolutionary idea of interlaced scanning to overcome the flicker problem of the 240-line with its 25 Hz frame rate. The 240-line system could have doubled its frame rate but this would have meant that the transmitted signal would have doubled in bandwidth, an unacceptable option as the video baseband bandwidth was required to be not more than 3 MHz.


Colour broadcasts started at similarly higher resolutions, first with the US NTSC color system in 1953, which was compatible with the earlier monochrome systems and therefore had the same 525 lines of resolution. European standards did not follow until the 1960s, when the PAL and SECAM color systems were added to the monochrome 625 line broadcasts.


The Nippon Hōsō Kyōkai (NHK, the Japan Broadcasting Corporation) began conducting research to "unlock the fundamental mechanism of video and sound interactions with the five human senses" in 1964, after the Tokyo Olympics. NHK set out to create an HDTV system that ended up scoring much higher in subjective tests than NTSC's previously dubbed "HDTV". This new system, NHK Color, created in 1972, included 1125 lines, a 5:3 aspect ratio and 60 Hz refresh rate. The Society of Motion Picture and Television Engineers (SMPTE), headed by Charles Ginsburg, became the testing and study authority for HDTV technology in the international theater. SMPTE would test HDTV systems from different companies from every conceivable perspective, but the problem of combining the different formats plagued the technology for many years.


There were four major HDTV systems tested by SMPTE in the late 1970s, and in 1979 an SMPTE study group released A Study of High Definition Television Systems:


Since the formal adoption of digital video broadcasting's (DVB) widescreen HDTV transmission modes in the early 2000s; the 525-line NTSC (and PAL-M) systems, as well as the European 625-line PAL and SECAM systems, are now regarded as standard definition television systems.


In 1949, France started its transmissions with an 819 lines system (with 737 active lines). The system was monochrome only, and was used only on VHF for the first French TV channel. It was discontinued in 1983.


In 1958, the Soviet Union developed Тransformator (Russian: Трансформатор, meaning Transformer), the first high-resolution (definition) television system capable of producing an image composed of 1,125 lines of resolution aimed at providing teleconferencing for military command. It was a research project and the system was never deployed by either the military or consumer broadcasting.


In 1979, the Japanese state broadcaster NHK first developed consumer high-definition television with a 5:3 display aspect ratio. The system, known as Hi-Vision or MUSE after its Multiple sub-Nyquist sampling encoding for encoding the signal, required about twice the bandwidth of the existing NTSC system but provided about four times the resolution (1080i/1125 lines). Satellite test broadcasts started in 1989, with regular testing starting in 1991 and regular broadcasting of BS-9ch commencing on November 25, 1994, which featured commercial and NHK programming.


In 1981, the MUSE system was demonstrated for the first time in the United States, using the same 5:3 aspect ratio as the Japanese system. Upon visiting a demonstration of MUSE in Washington, US President Ronald Reagan was impressed and officially declared it "a matter of national interest" to introduce HDTV to the US.


Several systems were proposed as the new standard for the US, including the Japanese MUSE system, but all were rejected by the FCC because of their higher bandwidth requirements. At this time, the number of television channels was growing rapidly and bandwidth was already a problem. A new standard had to be more efficient, needing less bandwidth for HDTV than the existing NTSC.


The limited standardization of analog HDTV in the 1990s did not lead to global HDTV adoption as technical and economic constraints at the time did not permit HDTV to use bandwidths greater than normal television.


Early HDTV commercial experiments, such as NHK's MUSE, required over four times the bandwidth of a standard-definition broadcast. Despite efforts made to reduce analog HDTV to about twice the bandwidth of SDTV, these television formats were still distributable only by satellite.


In addition, recording and reproducing an HDTV signal was a significant technical challenge in the early years of HDTV (Sony HDVS). Japan remained the only country with successful public broadcasting of analog HDTV, with seven broadcasters sharing a single channel.


Since 1972, International Telecommunication Union's radio telecommunications sector (ITU-R) had been working on creating a global recommendation for Analog HDTV. These recommendations, however, did not fit in the broadcasting bands which could reach home users. The standardization of MPEG-1 in 1993 also led to the acceptance of recommendations ITU-R BT.709. In anticipation of these standards the Digital Video Broadcasting (DVB) organisation was formed, an alliance of broadcasters, consumer electronics manufacturers and regulatory bodies. The DVB develops and agrees upon specifications which are formally standardised by ETSI.


DVB created first the standard for DVB-S digital satellite TV, DVB-C digital cable TV and DVB-T digital terrestrial TV. These broadcasting systems can be used for both SDTV and HDTV. In the US the Grand Alliance proposed ATSC as the new standard for SDTV and HDTV. Both ATSC and DVB were based on the MPEG-2 standard, although DVB systems may also be used to transmit video using the newer and more efficient H.264/MPEG-4 AVC compression standards. Common for all DVB standards is the use of highly efficient modulation techniques for further reducing bandwidth, and foremost for reducing receiver-hardware and antenna requirements.


In 1983, the International Telecommunication Union's radio telecommunications sector (ITU-R) set up a working party (IWP11/6) with the aim of setting a single international HDTV standard. One of the thornier issues concerned a suitable frame/field refresh rate, the world already having split into two camps, 25/50 Hz and 30/60 Hz, largely due to the differences in mains frequency. The IWP11/6 working party considered many views and throughout the 1980s served to encourage development in a number of video digital processing areas, not least conversion between the two main frame/field rates using motion vectors, which led to further developments in other areas. While a comprehensive HDTV standard was not in the end established, agreement on the aspect ratio was achieved.


Initially the existing 5:3 aspect ratio had been the main candidate but, due to the influence of widescreen cinema, the aspect ratio 16:9 (1.78) eventually emerged as being a reasonable compromise between 5:3 (1.67) and the common 1.85 widescreen cinema format. An aspect ratio of 16:9 was duly agreed upon at the first meeting of the IWP11/6 working party at the BBC's Research and Development establishment in Kingswood Warren. The resulting ITU-R Recommendation ITU-R BT.709-2 ("Rec. 709") includes the 16:9 aspect ratio, a specified colorimetry, and the scan modes 1080i (1,080 actively interlaced lines of resolution) and 1080p (1,080 progressively scanned lines). The British Freeview HD trials used MBAFF, which contains both progressive and interlaced content in the same encoding.


It also includes the alternative 1440×1152 HDMAC scan format. (According to some reports, a mooted 750-line (720p) format (720 progressively scanned lines) was viewed by some at the ITU as an enhanced television format rather than a true HDTV format, and so was not included, although 1920×1080i and 1280×720p systems for a range of frame and field rates were defined by several US SMPTE standards.)


HDTV technology was introduced in the United States in the late 1980s and made official in 1993 by the Digital HDTV Grand Alliance, a group of television, electronic equipment, communications companies consisting of AT&T Bell Labs, General Instrument, Philips, Sarnoff, Thomson, Zenith and the Massachusetts Institute of Technology. Field testing of HDTV at 199 sites in the United States was completed August 14, 1994. The first public HDTV broadcast in the United States occurred on July 23, 1996 when the Raleigh, North Carolina television station WRAL-HD began broadcasting from the existing tower of WRAL-TV southeast of Raleigh, winning a race to be first with the HD Model Station in Washington, D.C., which began broadcasting July 31, 1996 with the callsign WHD-TV, based out of the facilities of NBC owned and operated station WRC-TV. The American Advanced Television Systems Committee (ATSC) HDTV system had its public launch on October 29, 1998, during the live coverage of astronaut John Glenn's return mission to space on board the Space Shuttle Discovery. The signal was transmitted coast-to-coast, and was seen by the public in science centers, and other public theaters specially equipped to receive and display the broadcast.


The first HDTV transmissions in Europe, albeit not direct-to-home, began in 1990, when the Italian broadcaster RAI used the HD-MAC and MUSE HDTV technologies to broadcast the 1990 FIFA World Cup. The matches were shown in 8 cinemas in Italy and 2 in Spain. The connection with Spain was made via the Olympus satellite link from Rome to Barcelona and then with a fiber optic connection from Barcelona to Madrid. After some HDTV transmissions in Europe the standard was abandoned in the mid-1990s.


The first regular broadcasts started on January 1, 2004 when the Belgian company Euro1080 launched the HD1 channel with the traditional Vienna New Year's Concert. Test transmissions had been active since the IBC exhibition in September 2003, but the New Year's Day broadcast marked the official launch of the HD1 channel, and the official start of direct-to-home HDTV in Europe.


Euro1080, a division of the former and now bankrupt Belgian TV services company Alfacam, broadcast HDTV channels to break the pan-European stalemate of "no HD broadcasts mean no HD TVs bought means no HD broadcasts ..." and kick-start HDTV interest in Europe. The HD1 channel was initially free-to-air and mainly comprised sporting, dramatic, musical and other cultural events broadcast with a multi-lingual soundtrack on a rolling schedule of 4 or 5 hours per day.


These first European HDTV broadcasts used the 1080i format with MPEG-2 compression on a DVB-S signal from SES's Astra 1H satellite. Euro1080 transmissions later changed to MPEG-4/AVC compression on a DVB-S2 signal in line with subsequent broadcast channels in Europe.


Despite delays in some countries, the number of European HD channels and viewers has risen steadily since the first HDTV broadcasts, with SES's annual Satellite Monitor market survey for 2010 reporting more than 200 commercial channels broadcasting in HD from Astra satellites, 185 million HD capable TVs sold in Europe (£60 million in 2010 alone), and 20 million households (27% of all European digital satellite TV homes) watching HD satellite broadcasts (16 million via Astra satellites).


In December 2009 the United Kingdom became the first European country to deploy high definition content using the new DVB-T2 transmission standard, as specified in the Digital TV Group (DTG) D-book, on digital terrestrial television.


The Freeview HD service currently contains 10 HD channels (as of December 2013[update]) and was rolled out region by region across the UK in accordance with the digital switchover process, finally being completed in October 2012. However, Freeview HD is not the first HDTV service over digital terrestrial television in Europe;


If all three parameters are used, they are specified in the following form: [frame size][scanning system][frame or field rate] or [frame size]/[frame or field rate][scanning system].[citation needed] Often, frame size or frame rate can be dropped if its value is implied from context. In this case, the remaining numeric parameter is specified first, followed by the scanning system.


For example, 1920×1080p25 identifies progressive scanning format with 25 frames per second, each frame being 1,920 pixels wide and 1,080 pixels high. The 1080i25 or 1080i50 notation identifies interlaced scanning format with 25 frames (50 fields) per second, each frame being 1,920 pixels wide and 1,080 pixels high. The 1080i30 or 1080i60 notation identifies interlaced scanning format with 30 frames (60 fields) per second, each frame being 1,920 pixels wide and 1,080 pixels high. The 720p60 notation identifies progressive scanning format with 60 frames per second, each frame being 720 pixels high; 1,280 pixels horizontally are implied.


50 Hz systems support three scanning rates: 50i, 25p and 50p. 60 Hz systems support a much wider set of frame rates: 59.94i, 60i, 23.976p, 24p, 29.97p, 30p, 59.94p and 60p. In the days of standard definition television, the fractional rates were often rounded up to whole numbers, e.g. 23.976p was often called 24p, or 59.94i was often called 60i. 60 Hz high definition television supports both fractional and slightly different integer rates, therefore strict usage of notation is required to avoid ambiguity. Nevertheless, 29.97i/59.94i is almost universally called 60i, likewise 23.976p is called 24p.


For the commercial naming of a product, the frame rate is often dropped and is implied from context (e.g., a 1080i television set). A frame rate can also be specified without a resolution. For example, 24p means 24 progressive scan frames per second, and 50i means 25 interlaced frames per second.


There is no single standard for HDTV color support. Colors are typically broadcast using a (10-bits per channel) YUV color space but, depending on the underlying image generating technologies of the receiver, are then subsequently converted to a RGB color space using standardized algorithms. When transmitted directly through the Internet, the colors are typically pre-converted to 8-bit RGB channels for additional storage savings with the assumption that it will only be viewed only on a (sRGB) computer screen. As an added benefit to the original broadcasters, the losses of the pre-conversion essentially make these files unsuitable for professional TV re-broadcasting.


At a minimum, HDTV has twice the linear resolution of standard-definition television (SDTV), thus showing greater detail than either analog television or regular DVD. The technical standards for broadcasting HDTV also handle the 16:9 aspect ratio images without using letterboxing or anamorphic stretching, thus increasing the effective image resolution.


A very high resolution source may require more bandwidth than available in order to be transmitted without loss of fidelity. The lossy compression that is used in all digital HDTV storage and transmission systems will distort the received picture, when compared to the uncompressed source.


The optimum format for a broadcast depends upon the type of videographic recording medium used and the image's characteristics. For best fidelity to the source the transmitted field ratio, lines, and frame rate should match those of the source.


PAL, SECAM and NTSC frame rates technically apply only to analogue standard definition television, not to digital or high definition broadcasts. However, with the roll out of digital broadcasting, and later HDTV broadcasting, countries retained their heritage systems. HDTV in former PAL and SECAM countries operates at a frame rate of 25/50 Hz, while HDTV in former NTSC countries operates at 30/60 Hz.


Standard 35mm photographic film used for cinema projection has a much higher image resolution than HDTV systems, and is exposed and projected at a rate of 24 frames per second (frame/s). To be shown on standard television, in PAL-system countries, cinema film is scanned at the TV rate of 25 frame/s, causing a speedup of 4.1 percent, which is generally considered acceptable. In NTSC-system countries, the TV scan rate of 30 frame/s would cause a perceptible speedup if the same were attempted, and the necessary correction is performed by a technique called 3:2 Pulldown: Over each successive pair of film frames, one is held for three video fields (1/20 of a second) and the next is held for two video fields (1/30 of a second), giving a total time for the two frames of 1/12 of a second and thus achieving the correct average film frame rate.


Non-cinematic HDTV video recordings intended for broadcast are typically recorded either in 720p or 1080i format as determined by the broadcaster. 720p is commonly used for Internet distribution of high-definition video, because most computer monitors operate in progressive-scan mode. 720p also imposes less strenuous storage and decoding requirements compared to both 1080i and 1080p. 1080p/24, 1080i/30, 1080i/25, and 720p/30 is most often used on Blu-ray Disc.


In the US, residents in the line of sight of television station broadcast antennas can receive free, over the air programming with a television set with an ATSC tuner (most sets sold since 2009 have this). This is achieved with a TV aerial, just as it has been since the 1940s except now the major network signals are broadcast in high definition (ABC, Fox, and Ion Television broadcast at 720p resolution; CBS, My Network TV, NBC, PBS, and The CW at 1080i). As their digital signals more efficiently use the broadcast channel, many broadcasters are adding multiple channels to their signals. Laws about antennas were updated before the change to digital terrestrial broadcasts. These new laws prohibit home owners' associations and city government from banning the installation of antennas.


Additionally, cable-ready TV sets can display HD content without using an external box. They have a QAM tuner built-in and/or a card slot for inserting a CableCARD.


High-definition image sources include terrestrial broadcast, direct broadcast satellite, digital cable, IPTV (including GoogleTV Roku boxes and AppleTV or built into "Smart Televisions"), Blu-ray video disc (BD), and internet downloads.


Sony's PlayStation 3 has extensive HD compatibility because of its built in Blu-ray disc based player, so does Microsoft's Xbox 360 with the addition of Netflix and Windows Media Center HTPC streaming capabilities, and the Zune marketplace where users can rent or purchase digital HD content. Recently, Nintendo released a next generation high definition gaming platform, The Wii U, which includes TV remote control features in addition to IPTV streaming features like Netflix. The HD capabilities of the consoles has influenced some developers to port games from past consoles onto the PS3, Xbox 360 and Wii U, often with remastered or upscaled graphics.


HDTV can be recorded to D-VHS (Digital-VHS or Data-VHS), W-VHS (analog only), to an HDTV-capable digital video recorder (for example DirecTV's high-definition Digital video recorder, Sky HD's set-top box, Dish Network's VIP 622 or VIP 722 high-definition Digital video recorder receivers, or TiVo's Series 3 or HD recorders), or an HDTV-ready HTPC. Some cable boxes are capable of receiving or recording two or more broadcasts at a time in HDTV format, and HDTV programming, some included in the monthly cable service subscription price, some for an additional fee, can be played back with the cable company's on-demand feature.


The massive amount of data storage required to archive uncompressed streams meant that inexpensive uncompressed storage options were not available to the consumer. In 2008, the Hauppauge 1212 Personal Video Recorder was introduced. This device accepts HD content through component video inputs and stores the content in MPEG-2 format in a .ts file or in a Blu-ray compatible format .m2ts file on the hard drive or DVD burner of a computer connected to the PVR through a USB 2.0 interface. More recent systems are able to record a broadcast high definition program in its 'as broadcast' format or transcode to a format more compatible with Blu-ray.


Analog tape recorders with bandwidth capable of recording analog HD signals, such as W-VHS recorders, are no longer produced for the consumer market and are both expensive and scarce in the secondary market.


In the United States, as part of the FCC's plug and play agreement, cable companies are required to provide customers who rent HD set-top boxes with a set-top box with "functional" FireWire (IEEE 1394) on request. None of the direct broadcast satellite providers have offered this feature on any of their supported boxes, but some cable TV companies have. As of July 2004[update], boxes are not included in the FCC mandate. This content is protected by encryption known as 5C. This encryption can prevent duplication of content or simply limit the number of copies permitted, thus effectively denying most if not all fair use of the content.


It has been used for thousands of years for both fuel and as a construction material. It is an organic material, a natural composite of cellulose fibers (which are strong in tension) embedded in a matrix of lignin which resists compression. Wood is sometimes defined as only the secondary xylem in the stems of trees, or it is defined more broadly to include the same type of tissue elsewhere such as in the roots of trees or shrubs.[citation needed] In a living tree it performs a support function, enabling woody plants to grow large or to stand up by themselves. It also conveys water and nutrients between the leaves, other growing tissues, and the roots. Wood may also refer to other plant materials with comparable properties, and to material engineered from wood, or wood chips or fiber.


The Earth contains about 434 billion cubic meters of growing stock forest, 47% of which is commercial. As an abundant, carbon-neutral renewable resource, woody materials have been of intense interest as a source of renewable energy. In 1991, approximately 3.5 cubic kilometers of wood were harvested. Dominant uses were for furniture and building construction.


A 2011 discovery in the Canadian province of New Brunswick uncovered the earliest known plants to have grown wood, approximately 395 to 400 million years ago. Wood can be dated by carbon dating and in some species by dendrochronology to make inferences about when a wooden object was created.


People have used wood for millennia for many purposes, primarily as a fuel or as a construction material for making houses, tools, weapons, furniture, packaging, artworks, and paper. The year-to-year variation in tree-ring widths and isotopic abundances gives clues to the prevailing climate at that time.


Wood, in the strict sense, is yielded by trees, which increase in diameter by the formation, between the existing wood and the inner bark, of new woody layers which envelop the entire stem, living branches, and roots. This process is known as secondary growth; it is the result of cell division in the vascular cambium, a lateral meristem, and subsequent expansion of the new cells. Where there are clear seasons, growth can occur in a discrete annual or seasonal pattern, leading to growth rings; these can usually be most clearly seen on the end of a log, but are also visible on the other surfaces. If these seasons are annual these growth rings are referred to as annual rings. Where there is no seasonal difference growth rings are likely to be indistinct or absent.


If there are differences within a growth ring, then the part of a growth ring nearest the center of the tree, and formed early in the growing season when growth is rapid, is usually composed of wider elements. It is usually lighter in color than that near the outer portion of the ring, and is known as earlywood or springwood. The outer portion formed later in the season is then known as the latewood or summerwood. However, there are major differences, depending on the kind of wood (see below).


A knot is a particular type of imperfection in a piece of wood; it will affect the technical properties of the wood, usually reducing the local strength and increasing the tendency for splitting along the wood grain, but may be exploited for visual effect. In a longitudinally sawn plank, a knot will appear as a roughly circular "solid" (usually darker) piece of wood around which the grain of the rest of the wood "flows" (parts and rejoins). Within a knot, the direction of the wood (grain direction) is up to 90 degrees different from the grain direction of the regular wood.


In the tree a knot is either the base of a side branch or a dormant bud. A knot (when the base of a side branch) is conical in shape (hence the roughly circular cross-section) with the inner tip at the point in stem diameter at which the plant's vascular cambium was located when the branch formed as a bud.


During the development of a tree, the lower limbs often die, but may remain attached for a time, sometimes years. Subsequent layers of growth of the attaching stem are no longer intimately joined with the dead limb, but are grown around it. Hence, dead branches produce knots which are not attached, and likely to drop out after the tree has been sawn into boards.


In grading lumber and structural timber, knots are classified according to their form, size, soundness, and the firmness with which they are held in place. This firmness is affected by, among other factors, the length of time for which the branch was dead while the attaching stem continued to grow.


Knots do not necessarily influence the stiffness of structural timber, this will depend on the size and location. Stiffness and elastic strength are more dependent upon the sound wood than upon localized defects. The breaking strength is very susceptible to defects. Sound knots do not weaken wood when subject to compression parallel to the grain.


In some decorative applications, wood with knots may be desirable to add visual interest. In applications where wood is painted, such as skirting boards, fascia boards, door frames and furniture, resins present in the timber may continue to 'bleed' through to the surface of a knot for months or even years after manufacture and show as a yellow or brownish stain. A knot primer paint or solution, correctly applied during preparation, may do much to reduce this problem but it is difficult to control completely, especially when using mass-produced kiln-dried timber stocks.


Heartwood (or duramen) is wood that as a result of a naturally occurring chemical transformation has become more resistant to decay. Heartwood formation occurs spontaneously (it is a genetically programmed process). Once heartwood formation is complete, the heartwood is dead. Some uncertainty still exists as to whether heartwood is truly dead, as it can still chemically react to decay organisms, but only once.


Heartwood is often visually distinct from the living sapwood, and can be distinguished in a cross-section where the boundary will tend to follow the growth rings. For example, it is sometimes much darker. However, other processes such as decay or insect invasion can also discolor wood, even in woody plants that do not form heartwood, which may lead to confusion.


Sapwood (or alburnum) is the younger, outermost wood; in the growing tree it is living wood, and its principal functions are to conduct water from the roots to the leaves and to store up and give back according to the season the reserves prepared in the leaves. However, by the time they become competent to conduct water, all xylem tracheids and vessels have lost their cytoplasm and the cells are therefore functionally dead. All wood in a tree is first formed as sapwood. The more leaves a tree bears and the more vigorous its growth, the larger the volume of sapwood required. Hence trees making rapid growth in the open have thicker sapwood for their size than trees of the same species growing in dense forests. Sometimes trees (of species that do form heartwood) grown in the open may become of considerable size, 30 cm or more in diameter, before any heartwood begins to form, for example, in second-growth hickory, or open-grown pines.


The term heartwood derives solely from its position and not from any vital importance to the tree. This is evidenced by the fact that a tree can thrive with its heart completely decayed. Some species begin to form heartwood very early in life, so having only a thin layer of live sapwood, while in others the change comes slowly. Thin sapwood is characteristic of such species as chestnut, black locust, mulberry, osage-orange, and sassafras, while in maple, ash, hickory, hackberry, beech, and pine, thick sapwood is the rule. Others never form heartwood.


No definite relation exists between the annual rings of growth and the amount of sapwood. Within the same species the cross-sectional area of the sapwood is very roughly proportional to the size of the crown of the tree. If the rings are narrow, more of them are required than where they are wide. As the tree gets larger, the sapwood must necessarily become thinner or increase materially in volume. Sapwood is thicker in the upper portion of the trunk of a tree than near the base, because the age and the diameter of the upper sections are less.


When a tree is very young it is covered with limbs almost, if not entirely, to the ground, but as it grows older some or all of them will eventually die and are either broken off or fall off. Subsequent growth of wood may completely conceal the stubs which will however remain as knots. No matter how smooth and clear a log is on the outside, it is more or less knotty near the middle. Consequently, the sapwood of an old tree, and particularly of a forest-grown tree, will be freer from knots than the inner heartwood. Since in most uses of wood, knots are defects that weaken the timber and interfere with its ease of working and other properties, it follows that a given piece of sapwood, because of its position in the tree, may well be stronger than a piece of heartwood from the same tree.


It is remarkable that the inner heartwood of old trees remains as sound as it usually does, since in many cases it is hundreds, and in a few instances thousands, of years old. Every broken limb or root, or deep wound from fire, insects, or falling timber, may afford an entrance for decay, which, once started, may penetrate to all parts of the trunk. The larvae of many insects bore into the trees and their tunnels remain indefinitely as sources of weakness. Whatever advantages, however, that sapwood may have in this connection are due solely to its relative age and position.


If a tree grows all its life in the open and the conditions of soil and site remain unchanged, it will make its most rapid growth in youth, and gradually decline. The annual rings of growth are for many years quite wide, but later they become narrower and narrower. Since each succeeding ring is laid down on the outside of the wood previously formed, it follows that unless a tree materially increases its production of wood from year to year, the rings must necessarily become thinner as the trunk gets wider. As a tree reaches maturity its crown becomes more open and the annual wood production is lessened, thereby reducing still more the width of the growth rings. In the case of forest-grown trees so much depends upon the competition of the trees in their struggle for light and nourishment that periods of rapid and slow growth may alternate. Some trees, such as southern oaks, maintain the same width of ring for hundreds of years. Upon the whole, however, as a tree gets larger in diameter the width of the growth rings decreases.


Different pieces of wood cut from a large tree may differ decidedly, particularly if the tree is big and mature. In some trees, the wood laid on late in the life of a tree is softer, lighter, weaker, and more even-textured than that produced earlier, but in other trees, the reverse applies. This may or may not correspond to heartwood and sapwood. In a large log the sapwood, because of the time in the life of the tree when it was grown, may be inferior in hardness, strength, and toughness to equally sound heartwood from the same log. In a smaller tree, the reverse may be true.


In species which show a distinct difference between heartwood and sapwood the natural color of heartwood is usually darker than that of the sapwood, and very frequently the contrast is conspicuous (see section of yew log above). This is produced by deposits in the heartwood of chemical substances, so that a dramatic color difference does not mean a dramatic difference in the mechanical properties of heartwood and sapwood, although there may be a dramatic chemical difference.


Some experiments on very resinous Longleaf Pine specimens indicate an increase in strength, due to the resin which increases the strength when dry. Such resin-saturated heartwood is called "fat lighter". Structures built of fat lighter are almost impervious to rot and termites; however they are very flammable. Stumps of old longleaf pines are often dug, split into small pieces and sold as kindling for fires. Stumps thus dug may actually remain a century or more since being cut. Spruce impregnated with crude resin and dried is also greatly increased in strength thereby.


Since the latewood of a growth ring is usually darker in color than the earlywood, this fact may be used in judging the density, and therefore the hardness and strength of the material. This is particularly the case with coniferous woods. In ring-porous woods the vessels of the early wood not infrequently appear on a finished surface as darker than the denser latewood, though on cross sections of heartwood the reverse is commonly true. Except in the manner just stated the color of wood is no indication of strength.


Abnormal discoloration of wood often denotes a diseased condition, indicating unsoundness. The black check in western hemlock is the result of insect attacks. The reddish-brown streaks so common in hickory and certain other woods are mostly the result of injury by birds. The discoloration is merely an indication of an injury, and in all probability does not of itself affect the properties of the wood. Certain rot-producing fungi impart to wood characteristic colors which thus become symptomatic of weakness; however an attractive effect known as spalting produced by this process is often considered a desirable characteristic. Ordinary sap-staining is due to fungal growth, but does not necessarily produce a weakening effect.


In heartwood it occurs only in the first and last forms. Wood that is thoroughly air-dried retains 8–16% of the water in the cell walls, and none, or practically none, in the other forms. Even oven-dried wood retains a small percentage of moisture, but for all except chemical purposes, may be considered absolutely dry.


The general effect of the water content upon the wood substance is to render it softer and more pliable. A similar effect of common observation is in the softening action of water on rawhide, paper, or cloth. Within certain limits, the greater the water content, the greater its softening effect.


Drying produces a decided increase in the strength of wood, particularly in small specimens. An extreme example is the case of a completely dry spruce block 5 cm in section, which will sustain a permanent load four times as great as a green (undried) block of the same size will.


The greatest strength increase due to drying is in the ultimate crushing strength, and strength at elastic limit in endwise compression; these are followed by the modulus of rupture, and stress at elastic limit in cross-bending, while the modulus of elasticity is least affected.


Wood is a heterogeneous, hygroscopic, cellular and anisotropic material. It consists of cells, and the cell walls are composed of micro-fibrils of cellulose (40% – 50%) and hemicellulose (15% – 25%) impregnated with lignin (15% – 30%).


In coniferous or softwood species the wood cells are mostly of one kind, tracheids, and as a result the material is much more uniform in structure than that of most hardwoods. There are no vessels ("pores") in coniferous wood such as one sees so prominently in oak and ash, for example.


The structure of hardwoods is more complex. The water conducting capability is mostly taken care of by vessels: in some cases (oak, chestnut, ash) these are quite large and distinct, in others (buckeye, poplar, willow) too small to be seen without a hand lens. In discussing such woods it is customary to divide them into two large classes, ring-porous and diffuse-porous.


In ring-porous species, such as ash, black locust, catalpa, chestnut, elm, hickory, mulberry, and oak, the larger vessels or pores (as cross sections of vessels are called) are localised in the part of the growth ring formed in spring, thus forming a region of more or less open and porous tissue. The rest of the ring, produced in summer, is made up of smaller vessels and a much greater proportion of wood fibers. These fibers are the elements which give strength and toughness to wood, while the vessels are a source of weakness.[citation needed]


In diffuse-porous woods the pores are evenly sized so that the water conducting capability is scattered throughout the growth ring instead of being collected in a band or row. Examples of this kind of wood are alder, basswood,[citation needed] birch, buckeye, maple, willow,and the Populus species such as aspen, cottonwood and poplar. Some species, such as walnut and cherry, are on the border between the two classes, forming an intermediate group.[citation needed]


In temperate softwoods there often is a marked difference between latewood and earlywood. The latewood will be denser than that formed early in the season. When examined under a microscope the cells of dense latewood are seen to be very thick-walled and with very small cell cavities, while those formed first in the season have thin walls and large cell cavities. The strength is in the walls, not the cavities. Hence the greater the proportion of latewood the greater the density and strength. In choosing a piece of pine where strength or stiffness is the important consideration, the principal thing to observe is the comparative amounts of earlywood and latewood. The width of ring is not nearly so important as the proportion and nature of the latewood in the ring.


If a heavy piece of pine is compared with a lightweight piece it will be seen at once that the heavier one contains a larger proportion of latewood than the other, and is therefore showing more clearly demarcated growth rings. In white pines there is not much contrast between the different parts of the ring, and as a result the wood is very uniform in texture and is easy to work. In hard pines, on the other hand, the latewood is very dense and is deep-colored, presenting a very decided contrast to the soft, straw-colored earlywood.


It is not only the proportion of latewood, but also its quality, that counts. In specimens that show a very large proportion of latewood it may be noticeably more porous and weigh considerably less than the latewood in pieces that contain but little. One can judge comparative density, and therefore to some extent strength, by visual inspection.


No satisfactory explanation can as yet be given for the exact mechanisms determining the formation of earlywood and latewood. Several factors may be involved. In conifers, at least, rate of growth alone does not determine the proportion of the two portions of the ring, for in some cases the wood of slow growth is very hard and heavy, while in others the opposite is true. The quality of the site where the tree grows undoubtedly affects the character of the wood formed, though it is not possible to formulate a rule governing it. In general, however, it may be said that where strength or ease of working is essential, woods of moderate to slow growth should be chosen.


In ring-porous woods each season's growth is always well defined, because the large pores formed early in the season abut on the denser tissue of the year before.


In the case of the ring-porous hardwoods there seems to exist a pretty definite relation between the rate of growth of timber and its properties. This may be briefly summed up in the general statement that the more rapid the growth or the wider the rings of growth, the heavier, harder, stronger, and stiffer the wood. This, it must be remembered, applies only to ring-porous woods such as oak, ash, hickory, and others of the same group, and is, of course, subject to some exceptions and limitations.


In ring-porous woods of good growth it is usually the latewood in which the thick-walled, strength-giving fibers are most abundant. As the breadth of ring diminishes, this latewood is reduced so that very slow growth produces comparatively light, porous wood composed of thin-walled vessels and wood parenchyma. In good oak these large vessels of the earlywood occupy from 6 to 10 percent of the volume of the log, while in inferior material they may make up 25% or more. The latewood of good oak is dark colored and firm, and consists mostly of thick-walled fibers which form one-half or more of the wood. In inferior oak, this latewood is much reduced both in quantity and quality. Such variation is very largely the result of rate of growth.


Wide-ringed wood is often called "second-growth", because the growth of the young timber in open stands after the old trees have been removed is more rapid than in trees in a closed forest, and in the manufacture of articles where strength is an important consideration such "second-growth" hardwood material is preferred. This is particularly the case in the choice of hickory for handles and spokes. Here not only strength, but toughness and resilience are important. The results of a series of tests on hickory by the U.S. Forest Service show that:


In the diffuse-porous woods, the demarcation between rings is not always so clear and in some cases is almost (if not entirely) invisible to the unaided eye. Conversely, when there is a clear demarcation there may not be a noticeable difference in structure within the growth ring.


In diffuse-porous woods, as has been stated, the vessels or pores are even-sized, so that the water conducting capability is scattered throughout the ring instead of collected in the earlywood. The effect of rate of growth is, therefore, not the same as in the ring-porous woods, approaching more nearly the conditions in the conifers. In general it may be stated that such woods of medium growth afford stronger material than when very rapidly or very slowly grown. In many uses of wood, total strength is not the main consideration. If ease of working is prized, wood should be chosen with regard to its uniformity of texture and straightness of grain, which will in most cases occur when there is little contrast between the latewood of one season's growth and the earlywood of the next.


Structural material that resembles ordinary, "dicot" or conifer wood in its gross handling characteristics is produced by a number of monocot plants, and these also are colloquially called wood. Of these, bamboo, botanically a member of the grass family, has considerable economic importance, larger culms being widely used as a building and construction material in their own right and, these days, in the manufacture of engineered flooring, panels and veneer. Another major plant group that produce material that often is called wood are the palms. Of much less importance are plants such as Pandanus, Dracaena and Cordyline. With all this material, the structure and composition of the structural material is quite different from ordinary wood.


The single most revealing property of wood as an indicator of wood quality is specific gravity (Timell 1986), as both pulp yield and lumber strength are determined by it. Specific gravity is the ratio of the mass of a substance to the mass of an equal volume of water; density is the ratio of a mass of a quantity of a substance to the volume of that quantity and is expressed in mass per unit substance, e.g., grams per millilitre (g/cm3 or g/ml). The terms are essentially equivalent as long as the metric system is used. Upon drying, wood shrinks and its density increases. Minimum values are associated with green (water-saturated) wood and are referred to as basic specific gravity (Timell 1986).


Wood density is determined by multiple growth and physiological factors compounded into “one fairly easily measured wood characteristic” (Elliott 1970).


Age, diameter, height, radial growth, geographical location, site and growing conditions, silvicultural treatment, and seed source, all to some degree influence wood density. Variation is to be expected. Within an individual tree, the variation in wood density is often as great as or even greater than that between different trees (Timell 1986). Variation of specific gravity within the bole of a tree can occur in either the horizontal or vertical direction. :)


It is common to classify wood as either softwood or hardwood. The wood from conifers (e.g. pine) is called softwood, and the wood from dicotyledons (usually broad-leaved trees, e.g. oak) is called hardwood. These names are a bit misleading, as hardwoods are not necessarily hard, and softwoods are not necessarily soft. The well-known balsa (a hardwood) is actually softer than any commercial softwood. Conversely, some softwoods (e.g. yew) are harder than many hardwoods.


There is a strong relationship between the properties of wood and the properties of the particular tree that yielded it. The density of wood varies with species. The density of a wood correlates with its strength (mechanical properties). For example, mahogany is a medium-dense hardwood that is excellent for fine furniture crafting, whereas balsa is light, making it useful for model building. One of the densest woods is black ironwood.


The chemical composition of wood varies from species to species, but is approximately 50% carbon, 42% oxygen, 6% hydrogen, 1% nitrogen, and 1% other elements (mainly calcium, potassium, sodium, magnesium, iron, and manganese) by weight. Wood also contains sulfur, chlorine, silicon, phosphorus, and other elements in small quantity.


Aside from water, wood has three main components. Cellulose, a crystalline polymer derived from glucose, constitutes about 41–43%. Next in abundance is hemicellulose, which is around 20% in deciduous trees but near 30% in conifers. It is mainly five-carbon sugars that are linked in an irregular manner, in contrast to the cellulose. Lignin is the third component at around 27% in coniferous wood vs. 23% in deciduous trees. Lignin confers the hydrophobic properties reflecting the fact that it is based on aromatic rings. These three components are interwoven, and direct covalent linkages exist between the lignin and the hemicellulose. A major focus of the paper industry is the separation of the lignin from the cellulose, from which paper is made.


In chemical terms, the difference between hardwood and softwood is reflected in the composition of the constituent lignin. Hardwood lignin is primarily derived from sinapyl alcohol and coniferyl alcohol. Softwood lignin is mainly derived from coniferyl alcohol.


Aside from the lignocellulose, wood consists of a variety of low molecular weight organic compounds, called extractives. The wood extractives are fatty acids, resin acids, waxes and terpenes. For example, rosin is exuded by conifers as protection from insects. The extraction of these organic materials from wood provides tall oil, turpentine, and rosin.


Wood has a long history of being used as fuel, which continues to this day, mostly in rural areas of the world. Hardwood is preferred over softwood because it creates less smoke and burns longer. Adding a woodstove or fireplace to a home is often felt to add ambiance and warmth.


Wood has been an important construction material since humans began building shelters, houses and boats. Nearly all boats were made out of wood until the late 19th century, and wood remains in common use today in boat construction. Elm in particular was used for this purpose as it resisted decay as long as it was kept wet (it also served for water pipe before the advent of more modern plumbing).


Wood to be used for construction work is commonly known as lumber in North America. Elsewhere, lumber usually refers to felled trees, and the word for sawn planks ready for use is timber. In Medieval Europe oak was the wood of choice for all wood construction, including beams, walls, doors, and floors. Today a wider variety of woods is used: solid wood doors are often made from poplar, small-knotted pine, and Douglas fir.


New domestic housing in many parts of the world today is commonly made from timber-framed construction. Engineered wood products are becoming a bigger part of the construction industry. They may be used in both residential and commercial buildings as structural and aesthetic materials.


In buildings made of other materials, wood will still be found as a supporting material, especially in roof construction, in interior doors and their frames, and as exterior cladding.


Engineered wood products, glued building products "engineered" for application-specific performance requirements, are often used in construction and industrial applications. Glued engineered wood products are manufactured by bonding together wood strands, veneers, lumber or other forms of wood fiber with glue to form a larger, more efficient composite structural unit.


These products include glued laminated timber (glulam), wood structural panels (including plywood, oriented strand board and composite panels), laminated veneer lumber (LVL) and other structural composite lumber (SCL) products, parallel strand lumber, and I-joists. Approximately 100 million cubic meters of wood was consumed for this purpose in 1991. The trends suggest that particle board and fiber board will overtake plywood.


Wood unsuitable for construction in its native form may be broken down mechanically (into fibers or chips) or chemically (into cellulose) and used as a raw material for other building materials, such as engineered wood, as well as chipboard, hardboard, and medium-density fiberboard (MDF). Such wood derivatives are widely used: wood fibers are an important component of most paper, and cellulose is used as a component of some synthetic materials. Wood derivatives can also be used for kinds of flooring, for example laminate flooring.


Wood has always been used extensively for furniture, such as chairs and beds. It is also used for tool handles and cutlery, such as chopsticks, toothpicks, and other utensils, like the wooden spoon.


Further developments include new lignin glue applications, recyclable food packaging, rubber tire replacement applications, anti-bacterial medical agents, and high strength fabrics or composites. As scientists and engineers further learn and develop new techniques to extract various components from wood, or alternatively to modify wood, for example by adding components to wood, new more advanced products will appear on the marketplace. Moisture content electronic monitoring can also enhance next generation wood protection.


Wood has long been used as an artistic medium. It has been used to make sculptures and carvings for millennia. Examples include the totem poles carved by North American indigenous people from conifer trunks, often Western Red Cedar (Thuja plicata), and the Millennium clock tower, now housed in the National Museum of Scotland in Edinburgh. It is also used in woodcut printmaking, and for engraving.


Certain types of musical instruments, such as those of the violin family, the guitar, the clarinet and recorder, the xylophone, and the marimba, are traditionally made mostly or entirely of wood. The choice of wood may make a significant difference to the tone and resonant qualities of the instrument, and tonewoods have widely differing properties, ranging from the hard and dense african blackwood (used for the bodies of clarinets) to the light but resonant European spruce (Picea abies), which is traditionally used for the soundboards of violins. The most valuable tonewoods, such as the ripple sycamore (Acer pseudoplatanus), used for the backs of violins, combine acoustic properties with decorative color and grain which enhance the appearance of the finished instrument.


Despite their collective name, not all woodwind instruments are made entirely of wood. The reeds used to play them, however, are usually made from Arundo donax, a type of monocot cane plant.


Many types of sports equipment are made of wood, or were constructed of wood in the past. For example, cricket bats are typically made of white willow. The baseball bats which are legal for use in Major League Baseball are frequently made of ash wood or hickory, and in recent years have been constructed from maple even though that wood is somewhat more fragile. NBA courts have been traditionally made out of parquetry.


Many other types of sports and recreation equipment, such as skis, ice hockey sticks, lacrosse sticks and archery bows, were commonly made of wood in the past, but have since been replaced with more modern materials such as aluminium, fiberglass, carbon fiber, titanium, and composite materials. One noteworthy example of this trend is the golf club commonly known as the wood, the head of which was traditionally made of persimmon wood in the early days of the game of golf, but is now generally made of synthetic materials.


Little is known about the bacteria that degrade cellulose. Symbiotic bacteria in Xylophaga may play a role in the degradation of sunken wood; while bacteria such as Alphaproteobacteria, Flavobacteria, Actinobacteria, Clostridia, and Bacteroidetes have been detected in wood submerged over a year.


Somalis (Somali: Soomaali, Arabic: صومال) are an ethnic group inhabiting the Horn of Africa (Somali Peninsula). The overwhelming majority of Somalis speak the Somali language, which is part of the Cushitic branch of the Afro-Asiatic family. They are predominantly Sunni Muslim. Ethnic Somalis number around 16-20 million and are principally concentrated in Somalia (around 12.3 million), Ethiopia (4.6 million), Kenya (2.4 million), and Djibouti (464,600), with many also residing in parts of the Middle East, North America and Europe.


Irir Samaale, the oldest common ancestor of several Somali clans, is generally regarded as the source of the ethnonym Somali. The name "Somali" is, in turn, held to be derived from the words soo and maal, which together mean "go and milk" — a reference to the ubiquitous pastoralism of the Somali people. Another plausible etymology proposes that the term Somali is derived from the Arabic for "wealthy" (dhawamaal), again referring to Somali riches in livestock.


An Ancient Chinese document from the 9th century referred to the northern Somali coast — which was then called "Berbera" by Arab geographers in reference to the region's "Berber" (Cushitic) inhabitants — as Po-pa-li. The first clear written reference of the sobriquet Somali, however, dates back to the 15th century. During the wars between the Sultanate of Ifat based at Zeila and the Solomonic Dynasty, the Abyssinian Emperor had one of his court officials compose a hymn celebrating a military victory over the Sultan of Ifat's eponymous troops.


Ancient rock paintings in Somalia which date back to 5000 years have been found in the northern part of the country, depicting early life in the territory. The most famous of these is the Laas Geel complex, which contains some of the earliest known rock art on the African continent and features many elaborate pastoralist sketches of animal and human figures. In other places, such as the northern Dhambalin region, a depiction of a man on a horse is postulated as being one of the earliest known examples of a mounted huntsman.


Inscriptions have been found beneath many of the rock paintings, but archaeologists have so far been unable to decipher this form of ancient writing. During the Stone age, the Doian culture and the Hargeisan culture flourished here with their respective industries and factories.


The oldest evidence of burial customs in the Horn of Africa comes from cemeteries in Somalia dating back to 4th millennium BC. The stone implements from the Jalelo site in northern Somalia are said to be the most important link in evidence of the universality in palaeolithic times between the East and the West.


In antiquity, the ancestors of the Somali people were an important link in the Horn of Africa connecting the region's commerce with the rest of the ancient world. Somali sailors and merchants were the main suppliers of frankincense, myrrh and spices, items which were considered valuable luxuries by the Ancient Egyptians, Phoenicians, Mycenaeans and Babylonians.


According to most scholars, the ancient Land of Punt and its inhabitants formed part of the ethnogenesis of the Somali people. The ancient Puntites were a nation of people that had close relations with Pharaonic Egypt during the times of Pharaoh Sahure and Queen Hatshepsut. The pyramidal structures, temples and ancient houses of dressed stone littered around Somalia are said to date from this period.


In the classical era, several ancient city-states such as Opone, Essina, Sarapion, Nikon, Malao, Damo and Mosylon near Cape Guardafui, which competed with the Sabaeans, Parthians and Axumites for the wealthy Indo-Greco-Roman trade, also flourished in Somalia.


The birth of Islam on the opposite side of Somalia's Red Sea coast meant that Somali merchants, sailors and expatriates living in the Arabian Peninsula gradually came under the influence of the new religion through their converted Arab Muslim trading partners. With the migration of fleeing Muslim families from the Islamic world to Somalia in the early centuries of Islam and the peaceful conversion of the Somali population by Somali Muslim scholars in the following centuries, the ancient city-states eventually transformed into Islamic Mogadishu, Berbera, Zeila, Barawa and Merca, which were part of the Berberi civilization. The city of Mogadishu came to be known as the City of Islam, and controlled the East African gold trade for several centuries.


The Sultanate of Ifat, led by the Walashma dynasty with its capital at Zeila, ruled over parts of what is now eastern Ethiopia, Djibouti, and northern Somalia. The historian al-Umari records that Ifat was situated near the Red Sea coast, and states its size as 15 days travel by 20 days travel. Its army numbered 15,000 horsemen and 20,000 foot soldiers. Al-Umari also credits Ifat with seven "mother cities": Belqulzar, Kuljura, Shimi, Shewa, Adal, Jamme and Laboo.


In the Middle Ages, several powerful Somali empires dominated the regional trade including the Ajuran Sultanate, which excelled in hydraulic engineering and fortress building, the Sultanate of Adal, whose general Ahmad ibn Ibrahim al-Ghazi (Ahmed Gurey) was the first commander to use cannon warfare on the continent during Adal's conquest of the Ethiopian Empire, and the Sultanate of the Geledi, whose military dominance forced governors of the Omani empire north of the city of Lamu to pay tribute to the Somali Sultan Ahmed Yusuf.


In the late 19th century, after the Berlin conference had ended, European empires sailed with their armies to the Horn of Africa. The imperial clouds wavering over Somalia alarmed the Dervish leader Mohammed Abdullah Hassan, who gathered Somali soldiers from across the Horn of Africa and began one of the longest anti-colonial wars ever. The Dervish State successfully repulsed the British empire four times and forced it to retreat to the coastal region. As a result of its successes against the British, the Dervish State received support from the Ottoman and German empires. The Turks also named Hassan Emir of the Somali nation, and the Germans promised to officially recognize any territories the Dervishes were to acquire. After a quarter of a century of holding the British at bay, the Dervishes were finally defeated in 1920, when Britain for the first time in Africa used airplanes to bomb the Dervish capital of Taleex. As a result of this bombardment, former Dervish territories were turned into a protectorate of Britain. Italy similarly faced the same opposition from Somali Sultans and armies and did not acquire full control of parts of modern Somalia until the Fascist era in late 1927. This occupation lasted till 1941 and was replaced by a British military administration.


Following World War II, Britain retained control of both British Somaliland and Italian Somaliland as protectorates. In 1945, during the Potsdam Conference, the United Nations granted Italy trusteeship of Italian Somaliland, but only under close supervision and on the condition — first proposed by the Somali Youth League (SYL) and other nascent Somali political organizations, such as Hizbia Digil Mirifle Somali (HDMS) and the Somali National League (SNL) — that Somalia achieve independence within ten years. British Somaliland remained a protectorate of Britain until 1960.


To the extent that Italy held the territory by UN mandate, the trusteeship provisions gave the Somalis the opportunity to gain experience in political education and self-government. These were advantages that British Somaliland, which was to be incorporated into the new Somali state, did not have. Although in the 1950s British colonial officials attempted, through various administrative development efforts, to make up for past neglect, the protectorate stagnated. The disparity between the two territories in economic development and political experience would cause serious difficulties when it came time to integrate the two parts. Meanwhile, in 1948, under pressure from their World War II allies and to the dismay of the Somalis, the British "returned" the Haud (an important Somali grazing area that was presumably 'protected' by British treaties with the Somalis in 1884 and 1886) and the Ogaden to Ethiopia, based on a treaty they signed in 1897 in which the British ceded Somali territory to the Ethiopian Emperor Menelik in exchange for his help against plundering by Somali clans. Britain included the proviso that the Somali nomads would retain their autonomy, but Ethiopia immediately claimed sovereignty over them. This prompted an unsuccessful bid by Britain in 1956 to buy back the Somali lands it had turned over. Britain also granted administration of the almost exclusively Somali-inhabited Northern Frontier District (NFD) to Kenyan nationalists despite an informal plebiscite demonstrating the overwhelming desire of the region's population to join the newly formed Somali Republic.


A referendum was held in neighboring Djibouti (then known as French Somaliland) in 1958, on the eve of Somalia's independence in 1960, to decide whether or not to join the Somali Republic or to remain with France. The referendum turned out in favour of a continued association with France, largely due to a combined yes vote by the sizable Afar ethnic group and resident Europeans. There was also widespread vote rigging, with the French expelling thousands of Somalis before the referendum reached the polls. The majority of those who voted no were Somalis who were strongly in favour of joining a united Somalia, as had been proposed by Mahmoud Harbi, Vice President of the Government Council. Harbi was killed in a plane crash two years later. Djibouti finally gained its independence from France in 1977, and Hassan Gouled Aptidon, a Somali who had campaigned for a yes vote in the referendum of 1958, eventually wound up as Djibouti's first president (1977–1991).


British Somaliland became independent on 26 June 1960 as the State of Somaliland, and the Trust Territory of Somalia (the former Italian Somaliland) followed suit five days later. On 1 July 1960, the two territories united to form the Somali Republic, albeit within boundaries drawn up by Italy and Britain. A government was formed by Abdullahi Issa Mohamud and Muhammad Haji Ibrahim Egal other members of the trusteeship and protectorate governments, with Haji Bashir Ismail Yusuf as President of the Somali National Assembly, Aden Abdullah Osman Daar as the President of the Somali Republic and Abdirashid Ali Shermarke as Prime Minister (later to become President from 1967 to 1969). On 20 July 1961 and through a popular referendum, the people of Somalia ratified a new constitution, which was first drafted in 1960. In 1967, Muhammad Haji Ibrahim Egal became Prime Minister, a position to which he was appointed by Shermarke. Egal would later become the President of the autonomous Somaliland region in northwestern Somalia.


On 15 October 1969, while paying a visit to the northern town of Las Anod, Somalia's then President Abdirashid Ali Shermarke was shot dead by one of his own bodyguards. His assassination was quickly followed by a military coup d'état on 21 October 1969 (the day after his funeral), in which the Somali Army seized power without encountering armed opposition — essentially a bloodless takeover. The putsch was spearheaded by Major General Mohamed Siad Barre, who at the time commanded the army.


Alongside Barre, the Supreme Revolutionary Council (SRC) that assumed power after President Sharmarke's assassination was led by Lieutenant Colonel Salaad Gabeyre Kediye and Chief of Police Jama Korshel. The SRC subsequently renamed the country the Somali Democratic Republic, dissolved the parliament and the Supreme Court, and suspended the constitution.


The revolutionary army established large-scale public works programs and successfully implemented an urban and rural literacy campaign, which helped dramatically increase the literacy rate. In addition to a nationalization program of industry and land, the new regime's foreign policy placed an emphasis on Somalia's traditional and religious links with the Arab world, eventually joining the Arab League (AL) in 1974. That same year, Barre also served as chairman of the Organization of African Unity (OAU), the predecessor of the African Union (AU).


Somali people in the Horn of Africa are divided among different countries (Somalia, Djibouti, Ethiopia, and northeastern Kenya) that were artificially and some might say arbitrarily partitioned by the former imperial powers. Pan-Somalism is an ideology that advocates the unification of all ethnic Somalis once part of Somali empires such as the Ajuran Empire, the Adal Sultanate, the Gobroon Dynasty and the Dervish State under one flag and one nation. The Siad Barre regime actively promoted Pan-Somalism, which eventually led to the Ogaden War between Somalia on one side, and Ethiopia, Cuba and the Soviet Union on the other.


According to Y chromosome studies by Sanchez et al. (2005), Cruciani et al. (2004, 2007), the Somalis are paternally closely related to other Afro-Asiatic-speaking groups in Northeast Africa. Besides comprising the majority of the Y-DNA in Somalis, the E1b1b1a (formerly E3b1a) haplogroup also makes up a significant proportion of the paternal DNA of Ethiopians, Sudanese, Egyptians, Berbers, North African Arabs, as well as many Mediterranean populations. Sanchez et al. (2005) observed the M78 subclade of E1b1b in about 77% of their Somali male samples. According to Cruciani et al. (2007), the presence of this subhaplogroup in the Horn region may represent the traces of an ancient migration from Egypt/Libya. After haplogroup E1b1b, the second most frequently occurring Y-DNA haplogroup among Somalis is the West Asian haplogroup T (M70). It is observed in slightly more than 10% of Somali males. Haplogroup T, like haplogroup E1b1b, is also typically found among populations of Northeast Africa, North Africa, the Near East and the Mediterranean.


According to mtDNA studies by Holden (2005) and Richards et al. (2006), a significant proportion of the maternal lineages of Somalis consists of the M1 haplogroup. This mitochondrial clade is common among Ethiopians and North Africans, particularly Egyptians and Algerians. M1 is believed to have originated in Asia, where its parent M clade represents the majority of mtDNA lineages. This haplogroup is also thought to possibly correlate with the Afro-Asiatic language family:


According to an autosomal DNA study by Hodgson et al. (2014), the Afro-Asiatic languages were likely spread across Africa and the Near East by an ancestral population(s) carrying a newly identified non-African genetic component, which the researchers dub the "Ethio-Somali". This Ethio-Somali component is today most common among Afro-Asiatic-speaking populations in the Horn of Africa. It reaches a frequency peak among ethnic Somalis, representing the majority of their ancestry. The Ethio-Somali component is most closely related to the Maghrebi non-African genetic component, and is believed to have diverged from all other non-African ancestries at least 23,000 years ago. On this basis, the researchers suggest that the original Ethio-Somali carrying population(s) probably arrived in the pre-agricultural period from the Near East, having crossed over into northeastern Africa via the Sinai Peninsula. The population then likely split into two branches, with one group heading westward toward the Maghreb and the other moving south into the Horn.


The analysis of HLA antigens has also helped clarify the possible background of the Somali people, as the distribution of haplotype frequencies vary among population groups. According to Mohamoud et al. (2006):


The history of Islam in Somalia is as old as the religion itself. The early persecuted Muslims fled to various places in the region, including the city of Zeila in modern-day northern Somalia, so as to seek protection from the Quraysh. Somalis were among the first populations on the continent to embrace Islam. With very few exceptions, Somalis are entirely Muslims, the majority belonging to the Sunni branch of Islam and the Shafi`i school of Islamic jurisprudence, although a few are also adherents of the Shia Muslim denomination.


Qur'anic schools (also known as dugsi) remain the basic system of traditional religious instruction in Somalia. They provide Islamic education for children, thereby filling a clear religious and social role in the country. Known as the most stable local, non-formal system of education providing basic religious and moral instruction, their strength rests on community support and their use of locally made and widely available teaching materials. The Qur'anic system, which teaches the greatest number of students relative to other educational sub-sectors, is oftentimes the only system accessible to Somalis in nomadic as compared to urban areas. A study from 1993 found, among other things, that "unlike in primary schools where gender disparity is enormous, around 40 per cent of Qur'anic school pupils are girls; but the teaching staff have minimum or no qualification necessary to ensure intellectual development of children." To address these concerns, the Somali government on its own part subsequently established the Ministry of Endowment and Islamic Affairs, under which Qur'anic education is now regulated.


In the Somali diaspora, multiple Islamic fundraising events are held every year in cities like Birmingham, London, Toronto and Minneapolis, where Somali scholars and professionals give lectures and answer questions from the audience. The purpose of these events is usually to raise money for new schools or universities in Somalia, to help Somalis that have suffered as a consequence of floods and/or droughts, or to gather funds for the creation of new mosques like the Abuubakar-As-Saddique Mosque, which is currently undergoing construction in the Twin cities.


In addition, the Somali community has produced numerous important Muslim figures over the centuries, many of whom have significantly shaped the course of Islamic learning and practice in the Horn of Africa, the Arabian Peninsula and well beyond.


The clan groupings of the Somali people are important social units, and clan membership plays a central part in Somali culture and politics. Clans are patrilineal and are often divided into sub-clans, sometimes with many sub-divisions. The tombs of the founders of the Darod, Dir and Isaaq major clans as well as the Abgaal sub-clan of the Hawiye are all located in northern Somalia. Tradition holds this general area as an ancestral homeland of the Somali people.


Somali society is traditionally ethnically endogamous. So to extend ties of alliance, marriage is often to another ethnic Somali from a different clan. Thus, for example, a recent study observed that in 89 marriages contracted by men of the Dhulbahante clan, 55 (62%) were with women of Dhulbahante sub-clans other than those of their husbands; 30 (33.7%) were with women of surrounding clans of other clan families (Isaaq, 28; Hawiye, 3); and 3 (4.3%) were with women of other clans of the Darod clan family (Majerteen 2, Ogaden 1).


In 1975, the most prominent government reforms regarding family law in a Muslim country were set in motion in the Somali Democratic Republic, which put women and men, including husbands and wives, on complete equal footing. The 1975 Somali Family Law gave men and women equal division of property between the husband and wife upon divorce and the exclusive right to control by each spouse over his or her personal property.


Somalis constitute the largest ethnic group in Somalia, at approximately 85% of the nation's inhabitants. They are traditionally nomads, but since the late 20th century, many have moved to urban areas. While most Somalis can be found in Somalia proper, large numbers also live in Ethiopia, Djibouti, Kenya, Yemen, the Middle East, South Asia and Europe due to their seafaring tradition.


Civil strife in the early 1990s greatly increased the size of the Somali diaspora, as many of the best educated Somalis left for the Middle East, Europe and North America. In Canada, the cities of Toronto, Ottawa, Calgary, Edmonton, Montreal, Vancouver, Winnipeg and Hamilton all harbor Somali populations. Statistics Canada's 2006 census ranks people of Somali descent as the 69th largest ethnic group in Canada.


While the distribution of Somalis per country in Europe is hard to measure because the Somali community on the continent has grown so quickly in recent years, an official 2010 estimate reported 108,000 Somalis living in the United Kingdom. Somalis in Britain are largely concentrated in the cities of London, Sheffield, Bristol, Birmingham, Cardiff, Liverpool, Manchester, Leeds, and Leicester, with London alone accounting for roughly 78% of Britain's Somali population. There are also significant Somali communities in Sweden: 57,906 (2014); the Netherlands: 37,432 (2014); Norway: 38,413 (2015); Denmark: 18,645 (2014); and Finland: 16,721 (2014).


In the United States, Minneapolis, Saint Paul, Columbus, San Diego, Seattle, Washington, D.C., Houston, Atlanta, Los Angeles, Portland, Denver, Nashville, Green Bay, Lewiston, Portland, Maine and Cedar Rapids have the largest Somali populations.


An estimated 20,000 Somalis emigrated to the U.S. state of Minnesota some ten years ago and the Twin Cities (Minneapolis and Saint Paul) now have the highest population of Somalis in North America. The city of Minneapolis hosts hundreds of Somali-owned and operated businesses offering a variety of products, including leather shoes, jewelry and other fashion items, halal meat, and hawala or money transfer services. Community-based video rental stores likewise carry the latest Somali films and music. The number of Somalis has especially surged in the Cedar-Riverside area of Minneapolis.


There is a sizable Somali community in the United Arab Emirates. Somali-owned businesses line the streets of Deira, the Dubai city centre, with only Iranians exporting more products from the city at large. Internet cafés, hotels, coffee shops, restaurants and import-export businesses are all testimony to the Somalis' entrepreneurial spirit. Star African Air is also one of three Somali-owned airlines which are based in Dubai.


Besides their traditional areas of inhabitation in Greater Somalia, a Somali community mainly consisting of entrepreneurs, academics, and students also exists in Egypt. In addition, there is an historical Somali community in the general Sudan area. Primarily concentrated in the north and Khartoum, the expatriate community mainly consists of students as well as some businesspeople. More recently, Somali entrepreneurs have established themselves in Kenya, investing over $1.5 billion in the Somali enclave of Eastleigh alone. In South Africa, Somali businesspeople also provide most of the retail trade in informal settlements around the Western Cape province.


The Somali language is a member of the Cushitic branch of the Afro-Asiatic family. Its nearest relatives are the Afar and Saho languages. Somali is the best documented of the Cushitic languages, with academic studies of it dating from before 1900.


The exact number of speakers of Somali is unknown. One source estimates that there are 7.78 million speakers of Somali in Somalia itself and 12.65 million speakers globally. The Somali language is spoken by ethnic Somalis in Greater Somalia and the Somali diaspora.


Somali dialects are divided into three main groups: Northern, Benaadir and Maay. Northern Somali (or Northern-Central Somali) forms the basis for Standard Somali. Benaadir (also known as Coastal Somali) is spoken on the Benadir coast from Adale to south of Merca, including Mogadishu, as well as in the immediate hinterland. The coastal dialects have additional phonemes which do not exist in Standard Somali. Maay is principally spoken by the Digil and Mirifle (Rahanweyn) clans in the southern areas of Somalia.


A number of writing systems have been used over the years for transcribing the language. Of these, the Somali alphabet is the most widely used, and has been the official writing script in Somalia since the government of former President of Somalia Mohamed Siad Barre formally introduced it in October 1972. The script was developed by the Somali linguist Shire Jama Ahmed specifically for the Somali language, and uses all letters of the English Latin alphabet except p, v and z. Besides Ahmed's Latin script, other orthographies that have been used for centuries for writing Somali include the long-established Arabic script and Wadaad's writing. Indigenous writing systems developed in the twentieth century include the Osmanya, Borama and Kaddare scripts, which were invented by Osman Yusuf Kenadid, Abdurahman Sheikh Nuur and Hussein Sheikh Ahmed Kaddare, respectively.


In addition to Somali, Arabic, which is also an Afro-Asiatic tongue, is an official national language in both Somalia and Djibouti. Many Somalis speak it due to centuries-old ties with the Arab world, the far-reaching influence of the Arabic media, and religious education. Somalia and Djibouti are also both members of the Arab League.


The culture of Somalia is an amalgamation of traditions developed independently and through interaction with neighbouring and far away civilizations, such as other parts of Northeast Africa, the Arabian Peninsula, India and Southeast Asia.


The textile-making communities in Somalia are a continuation of an ancient textile industry, as is the culture of wood carving, pottery and monumental architecture that dominates Somali interiors and landscapes. The cultural diffusion of Somali commercial enterprise can be detected in its cuisine, which contains Southeast Asian influences. Due to the Somali people's passionate love for and facility with poetry, Somalia has often been referred to by scholars as a "Nation of Poets" and a "Nation of Bards" including, among others, the Canadian novelist Margaret Laurence.


All of these traditions, including festivals, martial arts, dress, literature, sport and games such as Shax, have immensely contributed to the enrichment of Somali heritage.


Somalis have a rich musical heritage centered on traditional Somali folklore. Most Somali songs are pentatonic. That is, they only use five pitches per octave in contrast to a heptatonic (seven note) scale, such as the major scale. At first listen, Somali music might be mistaken for the sounds of nearby regions such as Ethiopia, Sudan or Arabia, but it is ultimately recognizable by its own unique tunes and styles. Somali songs are usually the product of collaboration between lyricists (midho), songwriters (lahan) and singers ('odka or "voice").


Growing out of the Somali people's rich storytelling tradition, the first few feature-length Somali films and cinematic festivals emerged in the early 1960s, immediately after independence. Following the creation of the Somali Film Agency (SFA) regulatory body in 1975, the local film scene began to expand rapidly. The Somali filmmaker Ali Said Hassan concurrently served as the SFA's representative in Rome. In the 1970s and early 1980s, popular musicals known as riwaayado were the main driving force behind the Somali movie industry. Epic and period films as well as international co-productions followed suit, facilitated by the proliferation of video technology and national television networks. Said Salah Ahmed during this period directed his first feature film, The Somali Darwish (The Somalia Dervishes), devoted to the Dervish State. In the 1990s and 2000s, a new wave of more entertainment-oriented movies emerged. Referred to as Somaliwood, this upstart, youth-based cinematic movement has energized the Somali film industry and in the process introduced innovative storylines, marketing strategies and production techniques. The young directors Abdisalam Aato of Olol Films and Abdi Malik Isak are at the forefront of this quiet revolution.


Somali art is the artistic culture of the Somali people, both historic and contemporary. These include artistic traditions in pottery, music, architecture, wood carving and other genres. Somali art is characterized by its aniconism, partly as a result of the vestigial influence of the pre-Islamic mythology of the Somalis coupled with their ubiquitous Muslim beliefs. However, there have been cases in the past of artistic depictions representing living creatures, such as certain ancient rock paintings in northern Somalia, the golden birds on the Mogadishan canopies, and the plant decorations on religious tombs in southern Somalia. More typically, intricate patterns and geometric designs, bold colors and monumental architecture were the norm.


Additionally, henna is an important part of Somali culture. It is worn by Somali women on their hands, arms, feet and neck during weddings, Eid, Ramadan, and other festive occasions. Somali henna designs are similar to those in the Arabian peninsula, often featuring flower motifs and triangular shapes. The palm is also frequently decorated with a dot of henna and the fingertips are dipped in the dye. Henna parties are usually held before the wedding takes place. Somali women have likewise traditionally applied kohl (kuul) to their eyes. Usage of the eye cosmetic in the Horn region is believed to date to the ancient Land of Punt.


Football is the most popular sport amongst Somalis. Important competitions are the Somalia League and Somalia Cup. The multi-ethnic Ocean Stars, Somalia's national team, first participated at the Olympic Games in 1972 and has sent athletes to compete in most Summer Olympic Games since then. The equally diverse Somali beach soccer team also represents the country in international beach soccer competitions. In addition, several international footballers such as Mohammed Ahamed Jama, Liban Abdi, Ayub Daud and Abdisalam Ibrahim have played in European top divisions.