Before the early 20th century, treatments for infections were based primarily on medicinal folklore. Mixtures with antimicrobial properties that were used in treatments of infections were described over 2000 years ago. Many ancient cultures, including the ancient Egyptians and ancient Greeks, used specially selected mold and plant materials and extracts to treat infections. More recent observations made in the laboratory of antibiosis between microorganisms led to the discovery of natural antibacterials produced by microorganisms. Louis Pasteur observed, "if we could intervene in the antagonism observed between some bacteria, it would offer perhaps the greatest hopes for therapeutics". The term 'antibiosis', meaning "against life", was introduced by the French bacteriologist Jean Paul Vuillemin as a descriptive name of the phenomenon exhibited by these early antibacterial drugs. Antibiosis was first described in 1877 in bacteria when Louis Pasteur and Robert Koch observed that an airborne bacillus could inhibit the growth of Bacillus anthracis. These drugs were later renamed antibiotics by Selman Waksman, an American microbiologist, in 1942. Synthetic antibiotic chemotherapy as a science and development of antibacterials began in Germany with Paul Ehrlich in the late 1880s. Ehrlich noted certain dyes would color human, animal, or bacterial cells, whereas others did not. He then proposed the idea that it might be possible to create chemicals that would act as a selective drug that would bind to and kill bacteria without harming the human host. After screening hundreds of dyes against various organisms, in 1907, he discovered a medicinally useful drug, the synthetic antibacterial salvarsan now called arsphenamine.


The effects of some types of mold on infection had been noticed many times over the course of history (see: History of penicillin). In 1928, Alexander Fleming noticed the same effect in a Petri dish, where a number of disease-causing bacteria were killed by a fungus of the genus Penicillium. Fleming postulated that the effect is mediated by an antibacterial compound he named penicillin, and that its antibacterial properties could be exploited for chemotherapy. He initially characterized some of its biological properties, and attempted to use a crude preparation to treat some infections, but he was unable to pursue its further development without the aid of trained chemists.


The first sulfonamide and first commercially available antibacterial, Prontosil, was developed by a research team led by Gerhard Domagk in 1932 at the Bayer Laboratories of the IG Farben conglomerate in Germany. Domagk received the 1939 Nobel Prize for Medicine for his efforts. Prontosil had a relatively broad effect against Gram-positive cocci, but not against enterobacteria. Research was stimulated apace by its success. The discovery and development of this sulfonamide drug opened the era of antibacterials.


In 1939, coinciding with the start of World War II, Rene Dubos reported the discovery of the first naturally derived antibiotic, tyrothricin, a compound of 20% gramicidin and 80% tyrocidine, from B. brevis. It was one of the first commercially manufactured antibiotics universally and was very effective in treating wounds and ulcers during World War II. Gramicidin, however, could not be used systemically because of toxicity. Tyrocidine also proved too toxic for systemic usage. Research results obtained during that period were not shared between the Axis and the Allied powers during the war.


Florey and Chain succeeded in purifying the first penicillin, penicillin G, in 1942, but it did not become widely available outside the Allied military before 1945. Later, Norman Heatley developed the back extraction technique for efficiently purifying penicillin in bulk. The chemical structure of penicillin was determined by Dorothy Crowfoot Hodgkin in 1945. Purified penicillin displayed potent antibacterial activity against a wide range of bacteria and had low toxicity in humans. Furthermore, its activity was not inhibited by biological constituents such as pus, unlike the synthetic sulfonamides. The discovery of such a powerful antibiotic was unprecedented, and the development of penicillin led to renewed interest in the search for antibiotic compounds with similar efficacy and safety. For their successful development of penicillin, which Fleming had accidentally discovered but could not develop himself, as a therapeutic drug, Ernst Chain and Howard Florey shared the 1945 Nobel Prize in Medicine with Fleming. Florey credited Dubos with pioneering the approach of deliberately and systematically searching for antibacterial compounds, which had led to the discovery of gramicidin and had revived Florey's research in penicillin.


Vaccines rely on immune modulation or augmentation. Vaccination either excites or reinforces the immune competence of a host to ward off infection, leading to the activation of macrophages, the production of antibodies, inflammation, and other classic immune reactions. Antibacterial vaccines have been responsible for a drastic reduction in global bacterial diseases. Vaccines made from attenuated whole cells or lysates have been replaced largely by less reactogenic, cell-free vaccines consisting of purified components, including capsular polysaccharides and their conjugates, to protein carriers, as well as inactivated toxins (toxoids) and proteins.


Phage therapy is another option that is being looked into for treating resistant strains of bacteria. The way that researchers are doing this is by infecting pathogenic bacteria with their own viruses, more specifically, bacteriophages. Bacteriophages, also known simply as phages, are precisely bacterial viruses that infect bacteria by disrupting pathogenic bacterium lytic cycles. By disrupting the lytic cycles of bacterium, phages destroy their metabolism, which eventually results in the cell's death. Phages will insert their DNA into the bacterium, allowing their DNA to be transcribed. Once their DNA is transcribed the cell will proceed to make new phages and as soon as they are ready to be released, the cell will lyse. One of the worries about using phages to fight pathogens is that the phages will infect "good" bacteria, or the bacteria that are important in the everyday function of human beings. However, studies have proven that phages are very specific when they target bacteria, which makes researchers confident that bacteriophage therapy is the definite route to defeating antibiotic resistant bacteria.


In April 2013, the Infectious Disease Society of America (IDSA) reported that the weak antibiotic pipeline does not match bacteria's increasing ability to develop resistance. Since 2009, only 2 new antibiotics were approved in the United States. The number of new antibiotics approved for marketing per year declines continuously. The report identified seven antibiotics against the Gram-negative bacilli (GNB) currently in phase 2 or phase 3 clinical trials. However, these drugs do not address the entire spectrum of resistance of GNB. Some of these antibiotics are combination of existent treatments:


Possible improvements include clarification of clinical trial regulations by FDA. Furthermore, appropriate economic incentives could persuade pharmaceutical companies to invest in this endeavor. Antibiotic Development to Advance Patient Treatment (ADAPT) Act aims to fast track the drug development to combat the growing threat of 'superbugs'. Under this Act, FDA can approve antibiotics and antifungals treating life-threatening infections based on smaller clinical trials. The CDC will monitor the use of antibiotics and the emerging resistance, and publish the data. The FDA antibiotics labeling process, 'Susceptibility Test Interpretive Criteria for Microbial Organisms' or 'breakpoints', will provide accurate data to healthcare professionals. According to Allan Coukell, senior director for health programs at The Pew Charitable Trusts, "By allowing drug developers to rely on smaller datasets, and clarifying FDA's authority to tolerate a higher level of uncertainty for these drugs when making a risk/benefit calculation, ADAPT would make the clinical trials more feasible."


Windows 8 introduced major changes to the operating system's platform and user interface to improve its user experience on tablets, where Windows was now competing with mobile operating systems, including Android and iOS. In particular, these changes included a touch-optimized Windows shell based on Microsoft's "Metro" design language, the Start screen (which displays programs and dynamically updated content on a grid of tiles), a new platform for developing apps with an emphasis on touchscreen input, integration with online services (including the ability to sync apps and settings between devices), and Windows Store, an online store for downloading and purchasing new software. Windows 8 added support for USB 3.0, Advanced Format hard drives, near field communications, and cloud computing. Additional security features were introduced, such as built-in antivirus software, integration with Microsoft SmartScreen phishing filtering service and support for UEFI Secure Boot on supported devices with UEFI firmware, to prevent malware from infecting the boot process.


Windows 8 was released to a mixed critical reception. Although reaction towards its performance improvements, security enhancements, and improved support for touchscreen devices was positive, the new user interface of the operating system was widely criticized for being potentially confusing and difficult to learn (especially when used with a keyboard and mouse instead of a touchscreen). Despite these shortcomings, 60 million Windows 8 licenses have been sold through January 2013, a number which included both upgrades and sales to OEMs for new PCs.


Windows 8 development started before Windows 7 had shipped in 2009. At the Consumer Electronics Show in January 2011, it was announced that the next version of Windows would add support for ARM system-on-chips alongside the existing x86 processors produced by vendors, especially AMD and Intel. Windows division president Steven Sinofsky demonstrated an early build of the port on prototype devices, while Microsoft CEO Steve Ballmer announced the company's goal for Windows to be "everywhere on every kind of device without compromise." Details also began to surface about a new application framework for Windows 8 codenamed "Jupiter", which would be used to make "immersive" applications using XAML (similarly to Windows Phone and Silverlight) that could be distributed via a new packaging system and a rumored application store.


Three milestone releases of Windows 8 leaked to the general public. Milestone 1, Build 7850, was leaked on April 12, 2011. It was the first build where the text of a window was written centered instead of aligned to the left. It was also probably the first appearance of the Metro-style font, and its wallpaper had the text shhh... let's not leak our hard work. However, its detailed build number reveals that the build was created on September 22, 2010. The leaked copy edition was Enterprise edition. The OS still reads as "Windows 7". Milestone 2, Build 7955, was leaked on April 25, 2011. The traditional Blue Screen of Death (BSoD) was replaced by a new Black screen, although this was later scrapped. This build introduced a new ribbon in Windows Explorer. Build 7959, with minor changes but the first 64-bit version, was leaked on May 1, 2011. The "Windows 7" logo was temporarily replaced with text displaying "Microsoft Confidential". On June 17, 2011, build 7989 64-bit edition was leaked. It introduced a new boot screen featuring the same fish as the default Windows 7 Beta wallpaper, which was later scrapped, and the circling dots as featured in the final (although the final version comes with smaller circling dots throbber). It also had the text Welcome below them, although this was also scrapped.


The build was released for download later in the day in standard 32-bit and 64-bit versions, plus a special 64-bit version which included SDKs and developer tools (Visual Studio Express and Expression Blend) for developing Metro-style apps. The Windows Store was announced during the presentation, but was not available in this build. According to Microsoft, there were about 535,000 downloads of the developer preview within the first 12 hours of its release. Originally set to expire on March 11, 2012, in February 2012 the Developer Preview's expiry date was changed to January 15, 2013.


On February 29, 2012, Microsoft released Windows 8 Consumer Preview, the beta version of Windows 8, build 8250. Alongside other changes, the build removed the Start button from the taskbar for the first time since its debut on Windows 95; according to Windows manager Chaitanya Sareen, the Start button was removed to reflect their view that on Windows 8, the desktop was an "app" itself, and not the primary interface of the operating system. Windows president Steven Sinofsky said more than 100,000 changes had been made since the developer version went public. The day after its release, Windows 8 Consumer Preview had been downloaded over one million times. Like the Developer Preview, the Consumer Preview expired on January 15, 2013.


Many other builds were released until the Japan's Developers Day conference, when Steven Sinofsky announced that Windows 8 Release Preview (build 8400) would be released during the first week of June. On May 28, 2012, Windows 8 Release Preview (Standard Simplified Chinese x64 edition, not China-specific version, build 8400) was leaked online on various Chinese and BitTorrent websites. On May 31, 2012, Windows 8 Release Preview was released to the public by Microsoft. Major items in the Release Preview included the addition of Sports, Travel, and News apps, along with an integrated version of Adobe Flash Player in Internet Explorer. Like the Developer Preview and the Consumer Preview, the release preview expired on January 15, 2013.


On August 1, 2012, Windows 8 (build 9200) was released to manufacturing with the build number 6.2.9200.16384 . Microsoft planned to hold a launch event on October 25, 2012 and release Windows 8 for general availability on the next day. However, only a day after its release to manufacturing, a copy of the final version of Windows 8 Enterprise N (a version for European markets lacking bundled media players to comply with a court ruling) leaked online, followed by leaks of the final versions of Windows 8 Pro and Enterprise a few days later. On August 15, 2012, Windows 8 was made available to download for MSDN and TechNet subscribers. Windows 8 was made available to Software Assurance customers on August 16, 2012. Windows 8 was made available for students with a DreamSpark Premium subscription on August 22, 2012, earlier than advertised.


Relatively few changes were made from the Release Preview to the final version; these included updated versions of its pre-loaded apps, the renaming of Windows Explorer to File Explorer, the replacement of the Aero Glass theme from Windows Vista and 7 with a new flat and solid-colored theme, and the addition of new background options for the Start screen, lock screen, and desktop. Prior to its general availability on October 26, 2012, updates were released for some of Windows 8's bundled apps, and a "General Availability Cumulative Update" (which included fixes to improve performance, compatibility, and battery life) was released on Tuesday, October 9, 2012. Microsoft indicated that due to improvements to its testing infrastructure, general improvements of this nature are to be released more frequently through Windows Update instead of being relegated to OEMs and service packs only.


Microsoft began an advertising campaign centered around Windows 8 and its Surface tablet in October 2012, starting with its first television advertisement premiering on October 14, 2012. Microsoft's advertising budget of US$1.5–1.8 billion was significantly larger than the US$200 million campaign used to promote Windows 95. As part of its campaign, Microsoft set up 34 pop-up stores inside malls (primarily focusing on Surface), provided training for retail employees in partnership with Intel, and collaborated with the electronics store chain Best Buy to design expanded spaces to showcase devices. In an effort to make retail displays of Windows 8 devices more "personal", Microsoft also developed a character known in English-speaking markets as "Allison Brown", whose fictional profile (including personal photos, contacts, and emails) is also featured on demonstration units of Windows 8 devices.


In May 2013, Microsoft launched a new television campaign for Windows 8 illustrating the capabilities and pricing of Windows 8 tablets in comparison to the iPad, which featured the voice of Siri remarking on the iPad's limitations in a parody of Apple's "Get a Mac" advertisements. On June 12, 2013 during game 1 of the 2013 Stanley Cup Finals, Microsoft premiered the first ad in its "Windows Everywhere" campaign, which promoted Windows 8, Windows Phone 8, and the company's suite of online services as an interconnected platform.


New features and functionality in Windows 8 include a faster startup through UEFI integration and the new "Hybrid Boot" mode (which hibernates the Windows kernel on shutdown to speed up the subsequent boot), a new lock screen with a clock and notifications, and the ability for enterprise users to create live USB versions of Windows (known as Windows To Go). Windows 8 also adds native support for USB 3.0 devices, which allow for faster data transfers and improved power management with compatible devices, and hard disk 4KB Advanced Format support, as well as support for near field communication to facilitate sharing and communication between devices.


Windows Explorer, which has been renamed File Explorer, now includes a ribbon in place of the command bar. File operation dialog boxes have been updated to provide more detailed statistics, the ability to pause file transfers, and improvements in the ability to manage conflicts when copying files. A new "File History" function allows incremental revisions of files to be backed up to and restored from a secondary storage device, while Storage Spaces allows users to combine different sized hard disks into virtual drives and specify mirroring, parity, or no redundancy on a folder-by-folder basis.


Task Manager has been redesigned, including a new processes tab with the option to display fewer or more details of running applications and background processes, a heat map using different colors indicating the level of resource usage, network and disk counters, grouping by process type (e.g. applications, background processes and Windows processes), friendly names for processes and a new option which allows users to search the web to find information about obscure processes. Additionally, the Blue Screen of Death has been updated with a simpler and modern design with less technical information displayed.


New security features in Windows 8 include two new authentication methods tailored towards touchscreens (PINs and picture passwords), the addition of antivirus capabilities to Windows Defender (bringing it in parity with Microsoft Security Essentials). SmartScreen filtering integrated into Windows, Family Safety offers Parental controls, which allows parents to monitor and manage their children's activities on a device with activity reports and safety controls. Windows 8 also provides integrated system recovery through the new "Refresh" and "Reset" functions, including system recovery from USB drive. Windows 8's first security patches would be released on November 13, 2012; it would contain three fixes deemed "critical" by the company.


Windows 8 supports a feature of the UEFI specification known as "Secure boot", which uses a public-key infrastructure to verify the integrity of the operating system and prevent unauthorized programs such as bootkits from infecting the device's boot process. Some pre-built devices may be described as "certified" by Microsoft; these must have secure boot enabled by default, and provide ways for users to disable or re-configure the feature. ARM-based Windows RT devices must have secure boot permanently enabled.


Windows 8 provides heavier integration with online services from Microsoft and others. A user can now log in to Windows with a Microsoft account, which can be used to access services and synchronize applications and settings between devices. Windows 8 also ships with a client app for Microsoft's SkyDrive cloud storage service, which also allows apps to save files directly to SkyDrive. A SkyDrive client for the desktop and File Explorer is not included in Windows 8, and must be downloaded separately. Bundled multimedia apps are provided under the Xbox brand, including Xbox Music, Xbox Video, and the Xbox SmartGlass companion for use with an Xbox 360 console. Games can integrate into an Xbox Live hub app, which also allows users to view their profile and gamerscore. Other bundled apps provide the ability to link Flickr and Facebook. Due to Facebook Connect service changes, Facebook support is disabled in all bundled apps effective June 8, 2015.


Internet Explorer 10 is included as both a desktop program and a touch-optimized app, and includes increased support for HTML5, CSS3, and hardware acceleration. The Internet Explorer app does not support plugins or ActiveX components, but includes a version of Adobe Flash Player that is optimized for touch and low power usage. Initially, Adobe Flash would only work on sites included on a "Compatibility View" whitelist; however, after feedback from users and additional compatibility tests, an update in March 2013 changed this behavior to use a smaller blacklist of sites with known compatibility issues instead, allowing Flash to be used on most sites by default. The desktop version does not contain these limitations.


Windows 8 also incorporates improved support for mobile broadband; the operating system can now detect the insertion of a SIM card and automatically configure connection settings (including APNs and carrier branding), and reduce its internet usage in order to conserve bandwidth on metered networks. Windows 8 also adds an integrated airplane mode setting to globally disable all wireless connectivity as well. Carriers can also offer account management systems through Windows Store apps, which can be automatically installed as a part of the connection process and offer usage statistics on their respective tile.


Windows 8 introduces a new style of application, Windows Store apps. According to Microsoft developer Jensen Harris, these apps are to be optimized for touchscreen environments and are more specialized than current desktop applications. Apps can run either in a full-screen mode, or be snapped to the side of a screen. Apps can provide toast notifications on screen or animate their tiles on the Start screen with dynamic content. Apps can use "contracts"; a collection of hooks to provide common functionality that can integrate with other apps, including search and sharing. Apps can also provide integration with other services; for example, the People app can connect to a variety of different social networks and services (such as Facebook, Skype, and People service), while the Photos app can aggregate photos from services such as Facebook and Flickr.


Windows Store apps run within a new set of APIs known as Windows Runtime, which supports programming languages such as C, C++, Visual Basic .NET, C#, along with HTML5 and JavaScript. If written in some "high-level" languages, apps written for Windows Runtime can be compatible with both Intel and ARM versions of Windows, otherwise they are not binary code compatible. Components may be compiled as Windows Runtime Components, permitting consumption by all compatible languages. To ensure stability and security, apps run within a sandboxed environment, and require permissions to access certain functionality, such as accessing the Internet or a camera.


Retail versions of Windows 8 are only able to install these apps through Windows Store—a namesake distribution platform which offers both apps, and listings for desktop programs certified for comparability with Windows 8. A method to sideload apps from outside Windows Store is available to devices running Windows 8 Enterprise and joined to a domain; Windows 8 Pro and Windows RT devices that are not part of a domain can also sideload apps, but only after special product keys are obtained through volume licensing.


The term "Immersive app" had been used internally by Microsoft developers to refer to the apps prior to the first official presentation of Windows 8, after which they were referred to as "Metro-style apps" in reference to the Metro design language. The term was phased out in August 2012; a Microsoft spokesperson denied rumors that the change was related to a potential trademark issue, and stated that "Metro" was only a codename that would be replaced prior to Windows 8's release. Following these reports, the terms "Modern UI-style apps", "Windows 8-style apps" and "Windows Store apps" began to be used by various Microsoft documents and material to refer to the new apps. In an interview on September 12, 2012, Soma Somasegar (vice president of Microsoft's development software division) confirmed that "Windows Store apps" would be the official term for the apps. An MSDN page explaining the Metro design language uses the term "Modern design" to refer to the language as a whole.


Exceptions to the restrictions faced by Windows Store apps are given to web browsers. The user's default browser can distribute a Metro-style web browser in same package as the desktop version, which has access to functionality unavailable to other apps, such as being able to permanently run in the background, use multiple background processes, and use Windows API code instead of WinRT (allowing for code to be re-used with the desktop version, while still taking advantage of features available to Windows Store apps, such as charms). Microsoft advertises this exception privilege "New experience enabled" (formerly "Metro-style enabled").


The developers of both Chrome and Firefox committed to developing Metro-style versions of their browsers; while Chrome's "Windows 8 mode" uses a full-screen version of the existing desktop interface, Firefox's version (which was first made available on the "Aurora" release channel in September 2013) uses a touch-optimized interface inspired by the Android version of Firefox. In October 2013, Chrome's app was changed to mimic the desktop environment used by Chrome OS. Development of the Firefox app for Windows 8 has since been cancelled, citing a lack of user adoption for the beta versions.


Windows 8 introduces significant changes to the operating system's user interface, many of which are aimed at improving its experience on tablet computers and other touchscreen devices. The new user interface is based on Microsoft's Metro design language, and uses a Start screen similar to that of Windows Phone 7 as the primary means of launching applications. The Start screen displays a customizable array of tiles linking to various apps and desktop programs, some of which can display constantly updated information and content through "live tiles". As a form of multi-tasking, apps can be snapped to the side of a screen. Alongside the traditional Control Panel, a new simplified and touch-optimized settings app known as "PC Settings" is used for basic configuration and user settings. It does not include many of the advanced options still accessible from the normal Control Panel.


A vertical toolbar known as the charms (accessed by swiping from the right edge of a touchscreen, or pointing the cursor at hotspots in the right corners of a screen) provides access to system and app-related functions, such as search, sharing, device management, settings, and a Start button. The traditional desktop environment for running desktop applications is accessed via a tile on the Start screen. The Start button on the taskbar from previous versions of Windows has been converted into a hotspot in the lower-left corner of the screen, which displays a large tooltip displaying a thumbnail of the Start screen. Swiping from the left edge of a touchscreen or clicking in the top-left corner of the screen allows one to switch between apps and Desktop. Pointing the cursor in the top-left corner of the screen and moving down reveals a thumbnail list of active apps. Aside from the removal of the Start button and the replacement of the Aero Glass theme with a flatter and solid-colored design, the desktop interface on Windows 8 is similar to that of Windows 7.


Several notable features have been removed in Windows 8, beginning with the traditional Start menu. Support for playing DVD-Video was removed from Windows Media Player due to the cost of licensing the necessary decoders (especially for devices which do not include optical disc drives at all) and the prevalence of online streaming services. For the same reasons, Windows Media Center is not included by default on Windows 8, but Windows Media Center and DVD playback support can be purchased in the "Pro Pack" (which upgrades the system to Windows 8 Pro) or "Media Center Pack" add-on for Windows 8 Pro. As with prior versions, third-party DVD player software can still be used to enable DVD playback.


Backup and Restore, the backup component of Windows, is deprecated. It still ships with Windows 8 and continues to work on preset schedules, but is pushed to the background and can only be accessed through a Control Panel applet called "Windows 7 File Recovery".:76 Shadow Copy, a component of Windows Explorer that once saved previous versions of changed files, no longer protects local files and folders. It can only access previous versions of shared files stored on a Windows Server computer.:74 The subsystem on which these components worked, however, is still available for other software to use.:74


Microsoft released minimum hardware requirements for tablet and laplet devices to be "certified" for Windows 8, and defined a convertible form factor as a standalone device that combines the PC, display and rechargeable power source with a mechanically attached keyboard and pointing device in a single chassis. A convertible can be transformed into a tablet where the attached input devices are hidden or removed leaving the display as the only input mechanism. On March 12, 2013, Microsoft amended its certification requirements to only require that screens on tablets have a minimum resolution of 1024×768 (down from the previous 1366×768). The amended requirement is intended to allow "greater design flexibility" for future products.


Windows 8 is available in three different editions, of which the lowest version, branded simply as Windows 8, and Windows 8 Pro, were sold at retail in most countries, and as pre-loaded software on new computers. Each edition of Windows 8 includes all of the capabilities and features of the edition below it, and add additional features oriented towards their market segments. For example, Pro added BitLocker, Hyper-V, the ability to join a domain, and the ability to install Windows Media Center as a paid add-on. Users of Windows 8 can purchase a "Pro Pack" license that upgrades their system to Windows 8 Pro through Add features to Windows. This license also includes Windows Media Center. Windows 8 Enterprise contains additional features aimed towards business environments, and is only available through volume licensing. A port of Windows 8 for ARM architecture, Windows RT, is marketed as an edition of Windows 8, but was only included as pre-loaded software on devices specifically developed for it.


Windows 8 was distributed as a retail box product on DVD, and through a digital download that could be converted into DVD or USB install media. As part of a launch promotion, Microsoft offered Windows 8 Pro upgrades at a discounted price of US$39.99 online, or $69.99 for retail box from its launch until January 31, 2013; afterward the Windows 8 price has been $119.99 and the Pro price $199.99. Those who purchased new PCs pre-loaded with Windows 7 Home Basic, Home Premium, Professional, or Ultimate between June 2, 2012 and January 31, 2013 could digitally purchase a Windows 8 Pro upgrade for US$14.99. Several PC manufacturers offered rebates and refunds on Windows 8 upgrades obtained through the promotion on select models, such as Hewlett-Packard (in the U.S. and Canada on select models), and Acer (in Europe on selected Ultrabook models). During these promotions, the Windows Media Center add-on for Windows 8 Pro was also offered for free.


Unlike previous versions of Windows, Windows 8 was distributed at retail in "Upgrade" licenses only, which require an existing version of Windows to install. The "full version software" SKU, which was more expensive but could be installed on computers without an eligible OS or none at all, was discontinued. In lieu of full version, a specialized "System Builder" SKU was introduced. The "System Builder" SKU replaced the original equipment manufacturer (OEM) SKU, which was only allowed to be used on PCs meant for resale, but added a "Personal Use License" exemption that officially allowed its purchase and personal use by users on homebuilt computers.


Retail distribution of Windows 8 has since been discontinued in favor of Windows 8.1. Unlike 8, 8.1 is available as "full version software" at both retail and online for download that does not require a previous version of Windows in order to be installed. Pricing for these new copies remain identical. With the retail release returning to full version software for Windows 8.1, the "Personal Use License" exemption was removed from the OEM SKU, meaning that end users building their own PCs for personal use must use the full retail version in order to satisfy the Windows 8.1 licensing requirements. Windows 8.1 with Bing is a special OEM-specific SKU of Windows 8.1 subsidized by Microsoft's Bing search engine.


The three desktop editions of Windows 8 support 32-bit and 64-bit architectures; retail copies of Windows 8 include install DVDs for both architectures, while the online installer automatically installs the version corresponding with the architecture of the system's existing Windows installation. The 32-bit version runs on CPUs compatible with x86 architecture 3rd generation (known as IA-32) or newer, and can run 32-bit and 16-bit applications, although 16-bit support must be enabled first. (16-bit applications are developed for CPUs compatible with x86 2nd generation, first conceived in 1978. Microsoft started moving away from this architecture after Windows 95.)


Windows RT, the only edition of Windows 8 for systems with ARM processors, only supports applications included with the system (such as a special version of Office 2013), supplied through Windows Update, or Windows Store apps, to ensure that the system only runs applications that are optimized for the architecture. Windows RT does not support running IA-32 or x64 applications. Windows Store apps can either support both the x86 and ARM architectures, or compiled to support a specific architecture.


Following the unveiling of Windows 8, Microsoft faced criticism (particularly from free software supporters) for mandating that devices receiving its optional certification for Windows 8 have secure boot enabled by default using a key provided by Microsoft. Concerns were raised that secure boot could prevent or hinder the use of alternate operating systems such as Linux. In a post discussing secure boot on the Building Windows 8 blog, Microsoft developer Tony Mangefeste indicated that vendors would provide means to customize secure boot, stating that "At the end of the day, the customer is in control of their PC. Microsoft's philosophy is to provide customers with the best experience first, and allow them to make decisions themselves." Microsoft's certification guidelines for Windows 8 ultimately revealed that vendors would be required to provide means for users to re-configure or disable secure boot in their device's UEFI firmware. It also revealed that ARM devices (Windows RT) would be required to have secure boot permanently enabled, with no way for users to disable it. However, Tom Warren of The Verge noted that other vendors have implemented similar hardware restrictions on their own ARM-based tablet and smartphone products (including those running Microsoft's own Windows Phone platform), but still argued that Microsoft should "keep a consistent approach across ARM and x86, though, not least because of the number of users who'd love to run Android alongside Windows 8 on their future tablets." No mandate is made regarding the installation of third-party certificates that would enable running alternative programs.


Several notable video game developers criticized Microsoft for making its Windows Store a closed platform subject to its own regulations, as it conflicted with their view of the PC as an open platform. Markus "Notch" Persson (creator of the indie game Minecraft), Gabe Newell (co-founder of Valve Corporation and developer of software distribution platform Steam), and Rob Pardo from Activision Blizzard voiced concern about the closed nature of the Windows Store. However, Tom Warren of The Verge stated that Microsoft's addition of the Store was simply responding to the success of both Apple and Google in pursuing the "curated application store approach."


Reviews of the various editions of Windows 8 have been mixed. Tom Warren of The Verge said that although Windows 8's emphasis on touch computing was significant and risked alienating desktop users, a "tablet PC with Windows 8 makes an iPad feel immediately out of date" due to the capabilities of the operating system's hybrid model and increased focus on cloud services. David Pierce of The Verge described Windows 8 as "the first desktop operating system that understands what a computer is supposed to do in 2012" and praised Microsoft's "no compromise" approach and the operating system's emphasis on Internet connectivity and cloud services. Pierce also considered the Start Screen to be a "brilliant innovation for desktop computers" when compared with "folder-littered desktops on every other OS" because it allows users to interact with dynamic information. In contrast, an ExtremeTech article said it was Microsoft "flailing" and a review in PC Magazine condemned the Metro-style user interface. Some of the included apps in Windows 8 were considered to be basic and lacking in functionality, but the Xbox apps were praised for their promotion of a multi-platform entertainment experience. Other improvements and features (such as File History, Storage Spaces, and the updated Task Manager) were also regarded as positive changes. Peter Bright of Ars Technica wrote that while its user interface changes may overshadow them, Windows 8's improved performance, updated file manager, new storage functionality, expanded security features, and updated Task Manager were still positive improvements for the operating system. Bright also said that Windows 8's duality towards tablets and traditional PCs was an "extremely ambitious" aspect of the platform as well, but criticized Microsoft for emulating Apple's model of a closed distribution platform when implementing the Windows Store.


The interface of Windows 8 has been the subject of mixed reaction. Bright wrote that its system of hot corners and edge swiping "wasn't very obvious" due to the lack of instructions provided by the operating system on the functions accessed through the user interface, even by the video tutorial added on the RTM release (which only instructed users to point at corners of the screen or swipe from its sides). Despite this "stumbling block", Bright said that Windows 8's interface worked well in some places, but began to feel incoherent when switching between the "Metro" and desktop environments, sometimes through inconsistent means. Tom Warren of The Verge wrote that the new interface was "as stunning as it is surprising", contributing to an "incredibly personal" experience once it is customized by the user, but had a steep learning curve, and was awkward to use with a keyboard and mouse. He noted that while forcing all users to use the new touch-oriented interface was a risky move for Microsoft as a whole, it was necessary in order to push development of apps for the Windows Store. Others, such as Adrian Kingsley-Hughes from ZDNet, considered the interface to be "clumsy and impractical" due to its inconsistent design (going as far as considering it "two operating systems unceremoniously bolted together"), and concluded that "Windows 8 wasn't born out of a need or demand; it was born out of a desire on Microsoft's part to exert its will on the PC industry and decide to shape it in a direction—touch and tablets -- that allows it to compete against, and remain relevant in the face of Apple's iPad."


However, according to research firm NPD, sales of devices running Windows in the United States have declined 21 percent compared to the same time period in 2011. As the holiday shopping season wrapped up, Windows 8 sales continued to lag, even as Apple reported brisk sales. The market research firm IDC reported an overall drop in PC sales for the quarter, and said the drop may have been partly due to consumer reluctance to embrace the new features of the OS and poor support from OEM for these features. This capped the first year of declining PC sales to the Asia Pacific region, as consumers bought more mobile devices than Windows PCs.


Windows 8 surpassed Windows Vista in market share with a 5.1% usage rate according to numbers posted in July 2013 by Net Applications, with usage on a steady upward trajectory. However, intake of Windows 8 still lags behind that of Windows Vista and Windows 7 at the same point in their release cycles. Windows 8's tablet market share has also been growing steadily, with 7.4% of tablets running Windows in Q1 2013 according to Strategy Analytics, up from nothing just a year before. However, this is still well below Android and iOS, which posted 43.4% and 48.2% market share respectively, although both operating systems have been on the market much longer than Windows 8. Strategy Analytics also noted "a shortage of top tier apps" for Windows tablets despite Microsoft strategy of paying developers to create apps for the operating system (in addition to for Windows Phone).


In March 2013, Microsoft also amended its certification requirements to allow tablets to use the 1024×768 resolution as a minimum; this change is expected to allow the production of certified Windows 8 tablets in smaller form factors—a market which is currently dominated by Android-based tablets. Despite the reaction of industry experts, Microsoft reported that they had sold 100 million licenses in the first six months. This matched sales of Windows 7 over a similar period. This statistic includes shipments to channel warehouses which now need to be sold in order to make way for new shipments.


In February 2014, Bloomberg reported that Microsoft would be lowering the price of Windows 8 licenses by 70% for devices that retail under US$250; alongside the announcement that an update to the operating system would allow OEMs to produce devices with as little as 1 GB of RAM and 16 GB of storage, critics felt that these changes would help Windows compete against Linux-based devices in the low-end market, particularly those running Chrome OS. Microsoft had similarly cut the price of Windows XP licenses to compete against the early waves of Linux-based netbooks. Reports also indicated that Microsoft was planning to offer cheaper Windows 8 licenses to OEMs in exchange for setting Internet Explorer's default search engine to Bing. Some media outlets falsely reported that the SKU associated with this plan, "Windows 8.1 with Bing", was a variant which would be a free or low-cost version of Windows 8 for consumers using older versions of Windows. On April 2, 2014, Microsoft ultimately announced that it would be removing license fees entirely for devices with screens smaller than 9 inches, and officially confirmed the rumored "Windows 8.1 with Bing" OEM SKU on May 23, 2014.


In May 2014, the Government of China banned the internal purchase of Windows 8-based products under government contracts requiring "energy-efficient" devices. The Xinhua News Agency claimed that Windows 8 was being banned in protest of Microsoft's support lifecycle policy and the end of support for Windows XP (which, as of January 2014, had a market share of 49% in China), as the government "obviously cannot ignore the risks of running OS [sic] without guaranteed technical support." However, Ni Guangnan of the Chinese Academy of Sciences had also previously warned that Windows 8 could allegedly expose users to surveillance by the United States government due to its heavy use of internet-based services.


In June 2014, state broadcaster China Central Television (CCTV) broadcast a news story further characterizing Windows 8 as a threat to national security. The story featured an interview with Ni Guangnan, who stated that operating systems could aggregate "sensitive user information" that could be used to "understand the conditions and activities of our national economy and society", and alleged that per documents leaked by Edward Snowden, the U.S. government had worked with Microsoft to retrieve encrypted information. Yang Min, a computer scientist at Fudan University, also stated that "the security features of Windows 8 are basically to the benefit of Microsoft, allowing them control of the users' data, and that poses a big challenge to the national strategy for information security." Microsoft denied the claims in a number of posts on the Chinese social network Sina Weibo, which stated that the company had never "assisted any government in an attack of another government or clients" or provided client data to the U.S. government, never "provided any government the authority to directly visit" or placed any backdoors in its products and services, and that it had never concealed government requests for client data.


An upgrade to Windows 8 known as Windows 8.1 was officially announced by Microsoft on May 14, 2013. Following a presentation devoted to the upgrade at Build 2013, a public beta version of the upgrade was released on June 26, 2013. Windows 8.1 was released to OEM hardware partners on August 27, 2013, and released publicly as a free download through Windows Store on October 17, 2013. Volume license customers and subscribers to MSDN Plus and TechNet Plus were initially unable to obtain the RTM version upon its release; a spokesperson said the policy was changed to allow Microsoft to work with OEMs "to ensure a quality experience at general availability." However, after criticism, Microsoft reversed its decision and released the RTM build on MSDN and TechNet on September 9, 2013.


The upgrade addressed a number of criticisms faced by Windows 8 upon its release, with additional customization options for the Start screen, the restoration of a visible Start button on the desktop, the ability to snap up to four apps on a single display, and the ability to boot to the desktop instead of the Start screen. Windows 8's stock apps were also updated, a new Bing-based unified search system was added, SkyDrive was given deeper integration with the operating system, and a number of new stock apps, along with a tutorial, were added. Windows 8.1 also added support for 3D printing, Miracast media streaming, NFC printing, and Wi-Fi Direct.


At no more than 200 kilometres (120 mi) north to south and 130 kilometres (81 mi) east to west, Swaziland is one of the smallest countries in Africa. Despite its size, however, its climate and topography is diverse, ranging from a cool and mountainous highveld to a hot and dry lowveld. The population is primarily ethnic Swazis whose language is siSwati. They established their kingdom in the mid-18th century under the leadership of Ngwane III; the present boundaries were drawn up in 1881. After the Anglo-Boer War, Swaziland was a British protectorate from 1903 until 1967. It regained its independence on 6 September 1968.


Swaziland is a developing country with a small economy. Its GDP per capita of $9,714 means it is classified as a country with a lower-middle income. As a member of the Southern African Customs Union (SACU) and Common Market for Eastern and Southern Africa (COMESA), its main local trading partner is South Africa. Swaziland's currency, the lilangeni, is pegged to the South African rand. Swaziland's major overseas trading partners are the United States and the European Union. The majority of the country's employment is provided by its agricultural and manufacturing sectors. Swaziland is a member of the Southern African Development Community (SADC), the African Union, the Commonwealth of Nations and the United Nations.


Swaziland derives its name from a later king named Mswati II. KaNgwane, named for Ngwane III, is an alternative name for Swaziland the surname of whose royal house remains Nkhosi Dlamini. Nkhosi literally means "king". Mswati II was the greatest of the fighting kings of Swaziland, and he greatly extended the area of the country to twice its current size. The Emakhandzambili clans were initially incorporated into the kingdom with wide autonomy, often including grants of special ritual and political status. The extent of their autonomy however was drastically curtailed by Mswati, who attacked and subdued some of them in the 1850s.


In 1903, after British victory in the Anglo-Boer war, Swaziland became a British protectorate. Much of its early administration (for example, postal services) being carried out from South Africa until 1906 when the Transvaal colony was granted self-government. Following this, Swaziland was partitioned into European and non-European (or native reserves) areas with the former being two-thirds of the total land. Sobhuza's official coronation was in December 1921 after the regency of Labotsibeni after which he led an unsuccessful deputation to the Privy council in London in 1922 regarding the issue of the land.


The constitution for independent Swaziland was promulgated by Britain in November 1963 under the terms of which legislative and executive councils were established. This development was opposed by the Swazi National Council (liqoqo). Despite such opposition, elections took place and the first Legislative Council of Swaziland was constituted on 9 September 1964. Changes to the original constitution proposed by the Legislative Council were accepted by Britain and a new constitution providing for a House of Assembly and Senate was drawn up. Elections under this constitution were held in 1967.


Following the elections of 1973, the constitution of Swaziland was suspended by King Sobhuza II who thereafter ruled the country by decree until his death in 1982. At this point Sobhuza II had ruled Swaziland for 61 years, making him the longest ruling monarch in history. A regency followed his death, with Queen Regent Dzeliwe Shongwe being head of state until 1984 when she was removed by Liqoqo and replaced by Queen Mother Ntfombi Tfwala. Mswati III, the son of Ntfombi, was crowned king on 25 April 1986 as King and Ingwenyama of Swaziland.


The king appoints the prime minister from the legislature and also appoints a minority of legislators to both chambers of the Libandla (parliament) with help from an advisory council. The king is allowed by the constitution to appoint some members to parliament for special interests. These special interests are citizens who might have been left out by the electorate during the course of elections or did not enter as candidates. This is done to balance views in parliament. Special interests could be people of gender, race, disability, the business community, civic society, scholars, chiefs and so on.


The Swazi bicameral Parliament or Libandla consists of the Senate (30 seats; 10 members appointed by the House of Assembly and 20 appointed by the monarch; to serve five-year terms) and the House of Assembly (65 seats; 10 members appointed by the monarch and 55 elected by popular vote; to serve five-year terms). The elections are held every five years after dissolution of parliament by the king. The last elections were held on 20 September 2013. The balloting is done on a non-party basis in all categories. All election procedures are overseen by the elections and boundaries commission.


In 2005, the constitution was put into effect. There is still much debate in the country about the constitutional reforms. From the early seventies, there was active resistance to the royal hegemony. Despite complaints from progressive formations, support for the monarchy and the current political system remains strong among the majority of the population.[citation needed] Submissions were made by citizens around the country to commissions, including the constitutional draft committee, indicating that they would prefer to maintain the current situation.


Nominations take place at the chiefdoms. On the day of nomination, the name of the nominee is raised by a show of hand and the nominee is given an opportunity to indicate whether he or she accepts the nomination. If he or she accepts it, he or she must be supported by at least ten members of that chiefdom. The nominations are for the position of Member of Parliament, Constituency Headman (Indvuna) and the Constituency Executive Committee (Bucopho). The minimum number of nominees is four and the maximum is ten.


As noted above, there are 55 tinkhundla in Swaziland and each elects one representative to the House of Assembly of Swaziland. Each inkhundla has a development committee (bucopho) elected from the various constituency chiefdoms in its area for a five-year term. Bucopho bring to the inkhundla all matters of interest and concern to their various chiefdoms, and take back to the chiefdoms the decisions of the inkhundla. The chairman of the bucopho is elected at the inkhundla and is called indvuna ye nkhundla.


A small, landlocked kingdom, Swaziland is bordered in the North, West and South by the Republic of South Africa and by Mozambique in the East. Swaziland has a land area of 17,364 km2. Swaziland has four separate geographical regions. These run from North to South and are determined by altitude. Swaziland is located at approximately 26°30'S, 31°30'E. Swaziland has a wide variety of landscapes, from the mountains along the Mozambican border to savannas in the east and rain forest in the northwest. Several rivers flow through the country, such as the Great Usutu River.


About 75% of the population is employed in subsistence agriculture upon Swazi Nation Land (SNL). In contrast with the commercial farms, Swazi Nation Land suffers from low productivity and investment. This dual nature of the Swazi economy, with high productivity in textile manufacturing and in the industrialised agricultural TDLs on the one hand, and declining productivity subsistence agriculture (on SNL) on the other, may well explain the country's overall low growth, high inequality and unemployment.


Economic growth in Swaziland has lagged behind that of its neighbours. Real GDP growth since 2001 has averaged 2.8%, nearly 2 percentage points lower than growth in other Southern African Customs Union (SACU) member countries. Low agricultural productivity in the SNLs, repeated droughts, the devastating effect of HIV/AIDS and an overly large and inefficient government sector are likely contributing factors. Swaziland's public finances deteriorated in the late 1990s following sizeable surpluses a decade earlier. A combination of declining revenues and increased spending led to significant budget deficits.


The considerable spending did not lead to more growth and did not benefit the poor. Much of the increased spending has gone to current expenditures related to wages, transfers, and subsidies. The wage bill today constitutes over 15% of GDP and 55% of total public spending; these are some of the highest levels on the African continent. The recent rapid growth in SACU revenues has, however, reversed the fiscal situation, and a sizeable surplus was recorded since 2006. SACU revenues today account for over 60% of total government revenues. On the positive side, the external debt burden has declined markedly over the last 20 years, and domestic debt is almost negligible; external debt as a percent of GDP was less than 20% in 2006.


The Swazi economy is very closely linked to the economy of South Africa, from which it receives over 90% of its imports and to which it sends about 70% of its exports. Swaziland's other key trading partners are the United States and the EU, from whom the country has received trade preferences for apparel exports (under the African Growth and Opportunity Act – AGOA – to the US) and for sugar (to the EU). Under these agreements, both apparel and sugar exports did well, with rapid growth and a strong inflow of foreign direct investment. Textile exports grew by over 200% between 2000 and 2005 and sugar exports increasing by more than 50% over the same period.


Swaziland's currency is pegged to the South African Rand, subsuming Swaziland's monetary policy to South Africa. Customs duties from the Southern African Customs Union, which may equal as much as 70% of government revenue this year, and worker remittances from South Africa substantially supplement domestically earned income. Swaziland is not poor enough to merit an IMF program; however, the country is struggling to reduce the size of the civil service and control costs at public enterprises. The government is trying to improve the atmosphere for foreign direct investment.


83% of the total population adheres to Christianity, making it the most common religion in Swaziland. Anglican, Protestant and indigenous African churches, including African Zionist, constitute the majority of the Christians (40%), followed by Roman Catholicism at 20% of the population. On 18 July 2012, Ellinah Wamukoya, was elected Anglican Bishop of Swaziland, becoming the first woman to be a bishop in Africa. 15% of the population follows traditional religions; other non-Christian religions practised in the country include Islam (1%), the Bahá'í Faith (0.5%), and Hinduism (0.2%). There are 14 Jewish families.


In 2004, the Swaziland government acknowledged for the first time that it suffered an AIDS crisis, with 38.8% of tested pregnant women infected with HIV (see AIDS in Africa). The then Prime Minister Themba Dlamini declared a humanitarian crisis due to the combined effect of drought, land degradation, increased poverty, and HIV/AIDS. According to the 2011 UNAIDS Report, Swaziland is close to achieving universal access to HIV/AIDS treatment, defined as 80% coverage or greater. Estimates of treatment coverage range from 70% to 80% of those infected. Life expectancy had fallen from 61 years in 2000 to 32 years in 2009. Tuberculosis is also a significant problem, with an 18% mortality rate. Many patients have a multi-drug resistant strain, and 83% are co-infected with HIV.


Education in Swaziland begins with pre-school education for infants, primary, secondary and high school education for general education and training (GET), and universities and colleges at tertiary level. Pre-school education is usually for children 5-year or younger after that the students can enroll in a primary school anywhere in the country. In Swaziland early childhood care and education (ECCE) centres are in the form of preschools or neighbourhood care points (NCPs). In the country 21.6% of preschool age children have access to early childhood education.


The secondary and high school education system in Swaziland is a five-year programme divided into three years junior secondary and two years senior secondary. There is an external public examination (Junior Certificate) at the end of the junior secondary that learners have to pass to progress to the senior secondary level. The Examination Council of Swaziland (ECOS) administers this examination. At the end of the senior secondary level, learners sit for a public examination, the Swaziland General Certificate of Secondary Education (SGCSE) and International General Certificate of Secondary Education (IGCSE) which is accredited by the Cambridge International Examination (CIE). A few schools offer the Advanced Studies (AS) programme in their curriculum.


The University of Swaziland, Southern African Nazarene University, Swaziland Christian University are the institutions that offer university education in the country. A campus of Limkokwing University of Creative Technology can be found at Sidvwashini, a suburb of the capital Mbabane. There are some teaching and nursing assistant colleges around the country. Ngwane Teacher's College and William Pitcher College are the country's teaching colleges. The Good Shepherd Hospital in Siteki is home to the College for Nursing Assistants.


The main centre for technical training in Swaziland is the Swaziland College of Technology which is slated to become a full university. It aims to provide and facilitating high quality training and learning in technology and business studies in collaboration with the Commercial, Industrial and Public Sectors. Other technical and vocational institutions are the Gwamile Vocational and Commercial Training Institute located in Matsapha and the Manzini Industrial and Training Centre (MITC) in Manzini. Other vocational institutions include Nhlangano Agricultural Skills Training Center and Siteki Industrial Training Centre.


In addition to these institutions, Swaziland also has the Swaziland Institute of Management and Public Administration (SIMPA) and Institute of Development Management (IDM). SIMPA is a government owned management and development institute and IDM is a regional organisation in Botswana, Lesotho and Swaziland that provides training, consultancy, and research in management. The Mananga management centre was established as Mananga Agricultural Management Centre in 1972 as an International Management Development Centre catering for middle and senior managers, it is located at Ezulwini.


The Sangoma is a traditional diviner chosen by the ancestors of that particular family. The training of the Sangoma is called "kwetfwasa". At the end of the training, a graduation ceremony takes place where all the local sangoma come together for feasting and dancing. The diviner is consulted for various reasons, such the cause of sickness or even death. His diagnosis is based on "kubhula", a process of communication, through trance, with the natural superpowers. The Inyanga (a medical and pharmaceutical specialist in western terms) possesses the bone throwing skill ("kushaya ematsambo") used to determine the cause of the sickness.


Swaziland's most well-known cultural event is the annual Umhlanga Reed Dance. In the eight-day ceremony, girls cut reeds and present them to the queen mother and then dance. (There is no formal competition.) It is done in late August or early September. Only childless, unmarried girls can take part. The aims of the ceremony are to preserve girls' chastity, provide tribute labour for the Queen mother, and to encourage solidarity by working together. The royal family appoints a commoner maiden to be "induna" (captain) of the girls and she announces over the radio the dates of the ceremony. She will be an expert dancer and knowledgeable on royal protocol. One of the King's daughters will be her counterpart.


The Reed Dance today is not an ancient ceremony but a development of the old "umchwasho" custom. In "umchwasho", all young girls were placed in a female age-regiment. If any girl became pregnant outside of marriage, her family paid a fine of one cow to the local chief. After a number of years, when the girls had reached a marriageable age, they would perform labour service for the Queen Mother, ending with dancing and feasting. The country was under the chastity rite of "umchwasho" until 19 August 2005.


The English word "translation" derives from the Latin translatio (which itself comes from trans- and from fero, the supine form of which is latum—together meaning "a carrying across" or "a bringing across"). The modern Romance languages use equivalents of the English term "translation" that are derived from that same Latin source or from the alternative Latin traducere ("to lead across" or "to bring across"). The Slavic and Germanic languages (except in the case of the Dutch equivalent, "vertaling"—a "re-language-ing") likewise use calques of these Latin sources.


Despite occasional theoretical diversity, the actual practice of translation has hardly changed since antiquity. Except for some extreme metaphrasers in the early Christian period and the Middle Ages, and adapters in various periods (especially pre-Classical Rome, and the 18th century), translators have generally shown prudent flexibility in seeking equivalents — "literal" where possible, paraphrastic where necessary — for the original meaning and other crucial "values" (e.g., style, verse form, concordance with musical accompaniment or, in films, with speech articulatory movements) as determined from context.


In general, translators have sought to preserve the context itself by reproducing the original order of sememes, and hence word order — when necessary, reinterpreting the actual grammatical structure, for example, by shifting from active to passive voice, or vice versa. The grammatical differences between "fixed-word-order" languages (e.g. English, French, German) and "free-word-order" languages (e.g., Greek, Latin, Polish, Russian) have been no impediment in this regard. The particular syntax (sentence-structure) characteristics of a text's source language are adjusted to the syntactic requirements of the target language.


Generally, the greater the contact and exchange that have existed between two languages, or between those languages and a third one, the greater is the ratio of metaphrase to paraphrase that may be used in translating among them. However, due to shifts in ecological niches of words, a common etymology is sometimes misleading as a guide to current meaning in one or the other language. For example, the English actual should not be confused with the cognate French actuel ("present", "current"), the Polish aktualny ("present", "current," "topical," "timely," "feasible"), the Swedish aktuell ("topical", "presently of importance"), the Russian актуальный ("urgent", "topical") or the Dutch actueel.


The translator's role as a bridge for "carrying across" values between cultures has been discussed at least since Terence, the 2nd-century-BCE Roman adapter of Greek comedies. The translator's role is, however, by no means a passive, mechanical one, and so has also been compared to that of an artist. The main ground seems to be the concept of parallel creation found in critics such as Cicero. Dryden observed that "Translation is a type of drawing after life..." Comparison of the translator with a musician or actor goes back at least to Samuel Johnson’s remark about Alexander Pope playing Homer on a flageolet, while Homer himself used a bassoon.


Though earlier approaches to translation are less commonly used today, they retain importance when dealing with their products, as when historians view ancient or medieval records to piece together events which took place in non-Western or pre-Western environments. Also, though heavily influenced by Western traditions and practiced by translators taught in Western-style educational systems, Chinese and related translation traditions retain some theories and philosophies unique to the Chinese tradition.


Translation of material into Arabic expanded after the creation of Arabic script in the 5th century, and gained great importance with the rise of Islam and Islamic empires. Arab translation initially focused primarily on politics, rendering Persian, Greek, even Chinese and Indic diplomatic materials into Arabic. It later focused on translating classical Greek and Persian works, as well as some Chinese and Indian texts, into Arabic for scholarly study at major Islamic learning centers, such as the Al-Karaouine (Fes, Morocco), Al-Azhar (Cairo, Egypt), and the Al-Nizamiyya of Baghdad. In terms of theory, Arabic translation drew heavily on earlier Near Eastern traditions as well as more contemporary Greek and Persian traditions.


Arabic translation efforts and techniques are important to Western translation traditions due to centuries of close contacts and exchanges. Especially after the Renaissance, Europeans began more intensive study of Arabic and Persian translations of classical works as well as scientific and philosophical works of Arab and oriental origins. Arabic and, to a lesser degree, Persian became important sources of material and perhaps of techniques for revitalized Western traditions, which in time would overtake the Islamic and oriental traditions.


The movement to translate English and European texts transformed the Arabic and Ottoman Turkish languages, and new words, simplified syntax, and directness came to be valued over the previous convolutions. Educated Arabs and Turks in the new professions and the modernized civil service expressed skepticism, writes Christopher de Bellaigue, "with a freedom that is rarely witnessed today.... No longer was legitimate knowledge defined by texts in the religious schools, interpreted for the most part with stultifying literalness. It had come to include virtually any intellectual production anywhere in the world." One of the neologisms that, in a way, came to characterize the infusion of new ideas via translation was "darwiniya", or "Darwinism".


After World War I, when Britain and France divided up the Middle East's countries, apart from Turkey, between them, pursuant to the Sykes-Picot agreement—in violation of solemn wartime promises of postwar Arab autonomy—there came an immediate reaction: the Muslim Brotherhood emerged in Egypt, the House of Saud took over the Hijaz, and regimes led by army officers came to power in Iran and Turkey. "[B]oth illiberal currents of the modern Middle East," writes de Bellaigne, "Islamism and militarism, received a major impetus from Western empire-builders." As often happens in countries undergoing social crisis, the aspirations of the Muslim world's translators and modernizers, such as Muhammad Abduh, largely had to yield to retrograde currents.


Many non-transparent-translation theories draw on concepts from German Romanticism, the most obvious influence being the German theologian and philosopher Friedrich Schleiermacher. In his seminal lecture "On the Different Methods of Translation" (1813) he distinguished between translation methods that move "the writer toward [the reader]", i.e., transparency, and those that move the "reader toward [the author]", i.e., an extreme fidelity to the foreignness of the source text. Schleiermacher favored the latter approach; he was motivated, however, not so much by a desire to embrace the foreign, as by a nationalist desire to oppose France's cultural domination and to promote German literature.


Comparison of a back-translation with the original text is sometimes used as a check on the accuracy of the original translation, much as the accuracy of a mathematical operation is sometimes checked by reversing the operation. But the results of such reverse-translation operations, while useful as approximate checks, are not always precisely reliable. Back-translation must in general be less accurate than back-calculation because linguistic symbols (words) are often ambiguous, whereas mathematical symbols are intentionally unequivocal.


Mark Twain provided humorously telling evidence for the frequent unreliability of back-translation when he issued his own back-translation of a French translation of his short story, "The Celebrated Jumping Frog of Calaveras County". He published his back-translation in a 1903 volume together with his English-language original, the French translation, and a "Private History of the 'Jumping Frog' Story". The latter included a synopsized adaptation of his story that Twain stated had appeared, unattributed to Twain, in a Professor Sidgwick’s Greek Prose Composition (p. 116) under the title, "The Athenian and the Frog"; the adaptation had for a time been taken for an independent ancient Greek precursor to Twain's "Jumping Frog" story.


When a historic document survives only in translation, the original having been lost, researchers sometimes undertake back-translation in an effort to reconstruct the original text. An example involves the novel The Saragossa Manuscript by the Polish aristocrat Jan Potocki (1761–1815), who wrote the novel in French and anonymously published fragments in 1804 and 1813–14. Portions of the original French-language manuscript were subsequently lost; however, the missing fragments survived in a Polish translation that was made by Edmund Chojecki in 1847 from a complete French copy, now lost. French-language versions of the complete Saragossa Manuscript have since been produced, based on extant French-language fragments and on French-language versions that have been back-translated from Chojecki’s Polish version.


Translation has served as a school of writing for many authors. Translators, including monks who spread Buddhist texts in East Asia, and the early modern European translators of the Bible, in the course of their work have shaped the very languages into which they have translated. They have acted as bridges for conveying knowledge between cultures; and along with ideas, they have imported from the source languages, into their own languages, loanwords and calques of grammatical structures, idioms and vocabulary.


Interpreters have sometimes played crucial roles in history. A prime example is La Malinche, also known as Malintzin, Malinalli and Doña Marina, an early-16th-century Nahua woman from the Mexican Gulf Coast. As a child she had been sold or given to Maya slave-traders from Xicalango, and thus had become bilingual. Subsequently given along with other women to the invading Spaniards, she became instrumental in the Spanish conquest of Mexico, acting as interpreter, adviser, intermediary and lover to Hernán Cortés.


Web-based human translation is generally favored by companies and individuals that wish to secure more accurate translations. In view of the frequent inaccuracy of machine translations, human translation remains the most reliable, most accurate form of translation available. With the recent emergence of translation crowdsourcing, translation-memory techniques, and internet applications, translation agencies have been able to provide on-demand human-translation services to businesses, individuals, and enterprises.


Relying exclusively on unedited machine translation, however, ignores the fact that communication in human language is context-embedded and that it takes a person to comprehend the context of the original text with a reasonable degree of probability. It is certainly true that even purely human-generated translations are prone to error; therefore, to ensure that a machine-generated translation will be useful to a human being and that publishable-quality translation is achieved, such translations must be reviewed and edited by a human.


In Asia, the spread of Buddhism led to large-scale ongoing translation efforts spanning well over a thousand years. The Tangut Empire was especially efficient in such efforts; exploiting the then newly invented block printing, and with the full support of the government (contemporary sources describe the Emperor and his mother personally contributing to the translation effort, alongside sages of various nationalities), the Tanguts took mere decades to translate volumes that had taken the Chinese centuries to render.[citation needed]


The Arabs undertook large-scale efforts at translation. Having conquered the Greek world, they made Arabic versions of its philosophical and scientific works. During the Middle Ages, translations of some of these Arabic versions were made into Latin, chiefly at Córdoba in Spain. King Alfonso X el Sabio (Alphonse the Wise) of Castille in the 13th century promoted this effort by founding a Schola Traductorum (School of Translation) in Toledo. There Arabic texts, Hebrew texts, and Latin texts were translated into the other tongues by Muslim, Jewish and Christian scholars, who also argued the merits of their respective religions. Latin translations of Greek and original Arab works of scholarship and science helped advance European Scholasticism, and thus European science and culture.


The first great English translation was the Wycliffe Bible (ca. 1382), which showed the weaknesses of an underdeveloped English prose. Only at the end of the 15th century did the great age of English prose translation begin with Thomas Malory's Le Morte Darthur—an adaptation of Arthurian romances so free that it can, in fact, hardly be called a true translation. The first great Tudor translations are, accordingly, the Tyndale New Testament (1525), which influenced the Authorized Version (1611), and Lord Berners' version of Jean Froissart's Chronicles (1523–25).


Meanwhile, in Renaissance Italy, a new period in the history of translation had opened in Florence with the arrival, at the court of Cosimo de' Medici, of the Byzantine scholar Georgius Gemistus Pletho shortly before the fall of Constantinople to the Turks (1453). A Latin translation of Plato's works was undertaken by Marsilio Ficino. This and Erasmus' Latin edition of the New Testament led to a new attitude to translation. For the first time, readers demanded rigor of rendering, as philosophical and religious beliefs depended on the exact words of Plato, Aristotle and Jesus.


Throughout the 18th century, the watchword of translators was ease of reading. Whatever they did not understand in a text, or thought might bore readers, they omitted. They cheerfully assumed that their own style of expression was the best, and that texts should be made to conform to it in translation. For scholarship they cared no more than had their predecessors, and they did not shrink from making translations from translations in third languages, or from languages that they hardly knew, or—as in the case of James Macpherson's "translations" of Ossian—from texts that were actually of the "translator's" own composition.


The 19th century brought new standards of accuracy and style. In regard to accuracy, observes J.M. Cohen, the policy became "the text, the whole text, and nothing but the text", except for any bawdy passages and the addition of copious explanatory footnotes. In regard to style, the Victorians' aim, achieved through far-reaching metaphrase (literality) or pseudo-metaphrase, was to constantly remind readers that they were reading a foreign classic. An exception was the outstanding translation in this period, Edward FitzGerald's Rubaiyat of Omar Khayyam (1859), which achieved its Oriental flavor largely by using Persian names and discreet Biblical echoes and actually drew little of its material from the Persian original.


Translation of a text that is sung in vocal music for the purpose of singing in another language—sometimes called "singing translation"—is closely linked to translation of poetry because most vocal music, at least in the Western tradition, is set to verse, especially verse in regular patterns with rhyme. (Since the late 19th century, musical setting of prose and free verse has also been practiced in some art music, though popular music tends to remain conservative in its retention of stanzaic forms with or without refrains.) A rudimentary example of translating poetry for singing is church hymns, such as the German chorales translated into English by Catherine Winkworth.


Translation of sung texts is generally much more restrictive than translation of poetry, because in the former there is little or no freedom to choose between a versified translation and a translation that dispenses with verse structure. One might modify or omit rhyme in a singing translation, but the assignment of syllables to specific notes in the original musical setting places great challenges on the translator. There is the option in prose sung texts, less so in verse, of adding or deleting a syllable here and there by subdividing or combining notes, respectively, but even with prose the process is almost like strict verse translation because of the need to stick as closely as possible to the original prosody of the sung melodic line.


Translations of sung texts—whether of the above type meant to be sung or of a more or less literal type meant to be read—are also used as aids to audiences, singers and conductors, when a work is being sung in a language not known to them. The most familiar types are translations presented as subtitles or surtitles projected during opera performances, those inserted into concert programs, and those that accompany commercial audio CDs of vocal music. In addition, professional and amateur singers often sing works in languages they do not know (or do not know well), and translations are then used to enable them to understand the meaning of the words they are singing.


One of the first recorded instances of translation in the West was the rendering of the Old Testament into Greek in the 3rd century BCE. The translation is known as the "Septuagint", a name that refers to the seventy translators (seventy-two, in some versions) who were commissioned to translate the Bible at Alexandria, Egypt. Each translator worked in solitary confinement in his own cell, and according to legend all seventy versions proved identical. The Septuagint became the source text for later translations into many languages, including Latin, Coptic, Armenian and Georgian.


The period preceding, and contemporary with, the Protestant Reformation saw the translation of the Bible into local European languages—a development that contributed to Western Christianity's split into Roman Catholicism and Protestantism due to disparities between Catholic and Protestant versions of crucial words and passages (although the Protestant movement was largely based on other things, such as a perceived need for reformation of the Roman Catholic Church to eliminate corruption). Lasting effects on the religions, cultures and languages of their respective countries have been exerted by such Bible translations as Martin Luther's into German, Jakub Wujek's into Polish, and the King James Bible's translators' into English. Debate and religious schism over different translations of religious texts remain to this day, as demonstrated by, for example, the King James Only movement.


An airport is an aerodrome with facilities for flights to take off and land. Airports often have facilities to store and maintain aircraft, and a control tower. An airport consists of a landing area, which comprises an aerially accessible open space including at least one operationally active surface such as a runway for a plane to take off or a helipad, and often includes adjacent utility buildings such as control towers, hangars  and terminals. Larger airports may have fixed base operator services, airport aprons, air traffic control centres, passenger facilities such as restaurants and lounges, and emergency services.


The majority of the world's airports are non-towered, with no air traffic control presence. Busy airports have air traffic control (ATC) system. All airports use a traffic pattern to assure smooth traffic flow between departing and arriving aircraft. There are a number of aids available to pilots, though not all airports are equipped with them. Many airports have lighting that help guide planes using the runways and taxiways at night or in rain, snow, or fog. In the U.S. and Canada, the vast majority of airports, large and small, will either have some form of automated airport weather station, a human observer or a combination of the two. Air safety is an important concern in the operation of an airport, and airports often have their own safety services.


Most of the world's airports are owned by local, regional, or national government bodies who then lease the airport to private corporations who oversee the airport's operation. For example, in the United Kingdom the state-owned British Airports Authority originally operated eight of the nation's major commercial airports - it was subsequently privatized in the late 1980s, and following its takeover by the Spanish Ferrovial consortium in 2006, has been further divested and downsized to operating just five. Germany's Frankfurt Airport is managed by the quasi-private firm Fraport. While in India GMR Group operates, through joint ventures, Indira Gandhi International Airport and Rajiv Gandhi International Airport. Bengaluru International Airport and Chhatrapati Shivaji International Airport are controlled by GVK Group. The rest of India's airports are managed by the Airports Authority of India.


Airports are divided into landside and airside areas. Landside areas include parking lots, public transportation train stations and access roads. Airside areas include all areas accessible to aircraft, including runways, taxiways and aprons. Access from landside areas to airside areas is tightly controlled at most airports. Passengers on commercial flights access airside areas through terminals, where they can purchase tickets, clear security check, or claim luggage and board aircraft through gates. The waiting areas which provide passenger access to aircraft are typically called concourses, although this term is often used interchangeably with terminal.


Most major airports provide commercial outlets for products and services. Most of these companies, many of which are internationally known brands, are located within the departure areas. These include clothing boutiques and restaurants. Prices charged for items sold at these outlets are generally higher than those outside the airport. However, some airports now regulate costs to keep them comparable to "street prices". This term is misleading as prices often match the manufacturers' suggested retail price (MSRP) but are almost never discounted.[citation needed]


Airports may also contain premium and VIP services. The premium and VIP services may include express check-in and dedicated check-in counters. These services are usually reserved for First and Business class passengers, premium frequent flyers, and members of the airline's clubs. Premium services may sometimes be open to passengers who are members of a different airline's frequent flyer program. This can sometimes be part of a reciprocal deal, as when multiple airlines are part of the same alliance, or as a ploy to attract premium customers away from rival airlines.


Many large airports are located near railway trunk routes for seamless connection of multimodal transport, for instance Frankfurt Airport, Amsterdam Airport Schiphol, London Heathrow Airport, London Gatwick Airport and London Stansted Airport. It is also common to connect an airport and a city with rapid transit, light rail lines or other non-road public transport systems. Some examples of this would include the AirTrain JFK at John F. Kennedy International Airport in New York, Link Light Rail that runs from the heart of downtown Seattle to Seattle–Tacoma International Airport, and the Silver Line T at Boston's Logan International Airport by the Massachusetts Bay Transportation Authority (MBTA). Such a connection lowers risk of missed flights due to traffic congestion. Large airports usually have access also through controlled-access highways ('freeways' or 'motorways') from which motor vehicles enter either the departure loop or the arrival loop.


The distances passengers need to move within a large airport can be substantial. It is common for airports to provide moving walkways and buses. The Hartsfield–Jackson Atlanta International Airport has a tram that takes people through the concourses and baggage claim. Major airports with more than one terminal offer inter-terminal transportation, such as Mexico City International Airport, where the domestic building of Terminal 1 is connected by Aerotrén to Terminal 2, on the other side of the airport.


The title of "world's oldest airport" is disputed, but College Park Airport in Maryland, US, established in 1909 by Wilbur Wright, is generally agreed to be the world's oldest continually operating airfield, although it serves only general aviation traffic. Bisbee-Douglas International Airport in Arizona was declared "the first international airport of the Americas" by US president Franklin D. Roosevelt in 1943. Pearson Field Airport in Vancouver, Washington had a dirigible land in 1905 and planes in 1911 and is still in use. Bremen Airport opened in 1913 and remains in use, although it served as an American military field between 1945 and 1949. Amsterdam Airport Schiphol opened on September 16, 1916 as a military airfield, but only accepted civil aircraft from December 17, 1920, allowing Sydney Airport in Sydney, Australia—which started operations in January 1920—to claim to be one of the world's oldest continually operating commercial airports. Minneapolis-Saint Paul International Airport in Minneapolis-Saint Paul, Minnesota, opened in 1920 and has been in continuous commercial service since. It serves about 35,000,000 passengers each year and continues to expand, recently opening a new 11,000 foot (3,355 meter) runway. Of the airports constructed during this early period in aviation, it is one of the largest and busiest that is still currently operating. Rome Ciampino Airport, opened 1916, is also a contender, as well as the Don Mueang International Airport near Bangkok,Thailand, which opened in 1914. Increased aircraft traffic during World War I led to the construction of landing fields. Aircraft had to approach these from certain directions and this led to the development of aids for directing the approach and landing slope.


Following the war, some of these military airfields added civil facilities for handling passenger traffic. One of the earliest such fields was Paris – Le Bourget Airport at Le Bourget, near Paris. The first airport to operate scheduled international commercial services was Hounslow Heath Aerodrome in August 1919, but it was closed and supplanted by Croydon Airport in March 1920. In 1922, the first permanent airport and commercial terminal solely for commercial aviation was opened at Flughafen Devau near what was then Königsberg, East Prussia. The airports of this era used a paved "apron", which permitted night flying as well as landing heavier aircraft.


The first lighting used on an airport was during the latter part of the 1920s; in the 1930s approach lighting came into use. These indicated the proper direction and angle of descent. The colours and flash intervals of these lights became standardized under the International Civil Aviation Organization (ICAO). In the 1940s, the slope-line approach system was introduced. This consisted of two rows of lights that formed a funnel indicating an aircraft's position on the glideslope. Additional lights indicated incorrect altitude and direction.


Airport construction boomed during the 1960s with the increase in jet aircraft traffic. Runways were extended out to 3,000 m (9,800 ft). The fields were constructed out of reinforced concrete using a slip-form machine that produces a continual slab with no disruptions along the length. The early 1960s also saw the introduction of jet bridge systems to modern airport terminals, an innovation which eliminated outdoor passenger boarding. These systems became commonplace in the United States by the 1970s.


The majority of the world's airports are non-towered, with no air traffic control presence. However, at particularly busy airports, or airports with other special requirements, there is an air traffic control (ATC) system whereby controllers (usually ground-based) direct aircraft movements via radio or other communications links. This coordinated oversight facilitates safety and speed in complex operations where traffic moves in all three dimensions. Air traffic control responsibilities at airports are usually divided into at least two main areas: ground and tower, though a single controller may work both stations. The busiest airports also have clearance delivery, apron control, and other specialized ATC stations.


Ground Control is responsible for directing all ground traffic in designated "movement areas", except the traffic on runways. This includes planes, baggage trains, snowplows, grass cutters, fuel trucks, stair trucks, airline food trucks, conveyor belt vehicles and other vehicles. Ground Control will instruct these vehicles on which taxiways to use, which runway they will use (in the case of planes), where they will park, and when it is safe to cross runways. When a plane is ready to takeoff it will stop short of the runway, at which point it will be turned over to Tower Control. After a plane has landed, it will depart the runway and be returned to Ground Control.


Tower Control controls aircraft on the runway and in the controlled airspace immediately surrounding the airport. Tower controllers may use radar to locate an aircraft's position in three-dimensional space, or they may rely on pilot position reports and visual observation. They coordinate the sequencing of aircraft in the traffic pattern and direct aircraft on how to safely join and leave the circuit. Aircraft which are only passing through the airspace must also contact Tower Control in order to be sure that they remain clear of other traffic.


At all airports the use of a traffic pattern (often called a traffic circuit outside the U.S.) is possible. They may help to assure smooth traffic flow between departing and arriving aircraft. There is no technical need within modern aviation for performing this pattern, provided there is no queue. And due to the so-called SLOT-times, the overall traffic planning tend to assure landing queues are avoided. If for instance an aircraft approaches runway 17 (which has a heading of approx. 170 degrees) from the north (coming from 360/0 degrees heading towards 180 degrees), the aircraft will land as fast as possible by just turning 10 degrees and follow the glidepath, without orbit the runway for visual reasons, whenever this is possible. For smaller piston engined airplanes at smaller airfields without ILS equipment, things are very differently though.


Generally, this pattern is a circuit consisting of five "legs" that form a rectangle (two legs and the runway form one side, with the remaining legs forming three more sides). Each leg is named (see diagram), and ATC directs pilots on how to join and leave the circuit. Traffic patterns are flown at one specific altitude, usually 800 or 1,000 ft (244 or 305 m) above ground level (AGL). Standard traffic patterns are left-handed, meaning all turns are made to the left. One of the main reason for this is that pilots sit on the left side of the airplane, and a Left-hand patterns improves their visibility of the airport and pattern. Right-handed patterns do exist, usually because of obstacles such as a mountain, or to reduce noise for local residents. The predetermined circuit helps traffic flow smoothly because all pilots know what to expect, and helps reduce the chance of a mid-air collision.


At extremely large airports, a circuit is in place but not usually used. Rather, aircraft (usually only commercial with long routes) request approach clearance while they are still hours away from the airport, often before they even take off from their departure point. Large airports have a frequency called Clearance Delivery which is used by departing aircraft specifically for this purpose. This then allows aircraft to take the most direct approach path to the runway and land without worrying about interference from other aircraft. While this system keeps the airspace free and is simpler for pilots, it requires detailed knowledge of how aircraft are planning to use the airport ahead of time and is therefore only possible with large commercial airliners on pre-scheduled flights. The system has recently become so advanced that controllers can predict whether an aircraft will be delayed on landing before it even takes off; that aircraft can then be delayed on the ground, rather than wasting expensive fuel waiting in the air.


There are a number of aids available to pilots, though not all airports are equipped with them. A visual approach slope indicator (VASI) helps pilots fly the approach for landing. Some airports are equipped with a VHF omnidirectional range (VOR) to help pilots find the direction to the airport. VORs are often accompanied by a distance measuring equipment (DME) to determine the distance to the VOR. VORs are also located off airports, where they serve to provide airways for aircraft to navigate upon. In poor weather, pilots will use an instrument landing system (ILS) to find the runway and fly the correct approach, even if they cannot see the ground. The number of instrument approaches based on the use of the Global Positioning System (GPS) is rapidly increasing and may eventually be the primary means for instrument landings.


On runways, green lights indicate the beginning of the runway for landing, while red lights indicate the end of the runway. Runway edge lighting consists of white lights spaced out on both sides of the runway, indicating the edge. Some airports have more complicated lighting on the runways including lights that run down the centerline of the runway and lights that help indicate the approach (an approach lighting system, or ALS). Low-traffic airports may use pilot controlled lighting to save electricity and staffing costs.


Hazards to aircraft include debris, nesting birds, and reduced friction levels due to environmental conditions such as ice, snow, or rain. Part of runway maintenance is airfield rubber removal which helps maintain friction levels. The fields must be kept clear of debris using cleaning equipment so that loose material does not become a projectile and enter an engine duct (see foreign object damage). In adverse weather conditions, ice and snow clearing equipment can be used to improve traction on the landing strip. For waiting aircraft, equipment is used to spray special deicing fluids on the wings.