Headstone
A headstone, tombstone, or gravestone is a stele or marker, usually stone, that is placed over a grave.  It is traditional for burials in the Christian, Jewish, and Muslim religions, among others.  In most cases, it has the deceased's name, date of birth, and date of death inscribed on it, along with a personal message, or prayer, but may contain pieces of funerary art, especially details in stone relief.  In many parts of Europe, insetting a photograph of the deceased in a frame is very common.

Use
The stele (plural stelae), as it is called in an archaeological context, is one of the oldest forms of funerary art.  Originally, a tombstone was the stone lid of a stone coffin, or the coffin itself, and a gravestone was the stone slab (or ledger stone) that was laid flat over a grave. Now, all three terms ("stele", "tombstone" or "gravestone") are also used for markers set (usually upright) at the head of the grave. Some graves in the 18th century also contained footstones to demarcate the foot end of the grave. This sometimes developed into full kerb sets that marked the whole perimeter of the grave. Footstones were rarely annotated with more than the deceased's initials and year of death, and sometimes a memorial mason and plot reference number. Many cemeteries and churchyards have removed those extra stones to ease grass cutting by machine mower. In some UK cemeteries, the principal, and indeed only, marker is placed at the foot of the grave.
Owing to soil movement and downhill creep on gentle slopes, older headstones and footstones can often be found tilted at an angle. Over time, this movement can result in the stones being sited several metres away from their original location.Graves and any related memorials are a focus for mourning and remembrance. The names of relatives are often added to a gravestone over the years, so that one marker may chronicle the passing of an entire family spread over decades. Since gravestones and a plot in a cemetery or churchyard cost money, they are also a symbol of wealth or prominence in a community. Some gravestones were even commissioned and erected to their own memory by people who were still living, as a testament to their wealth and status. In a Christian context, the very wealthy often erected elaborate memorials within churches rather than having simply external gravestones. Crematoria frequently offer similar alternatives to families who do not have a grave to mark, but who want a focus for their mourning and for remembrance. Carved or cast commemorative plaques inside the crematorium for example may serve this purpose.

Materials
A cemetery may follow national codes of practice or independently prescribe the size and use of certain materials, especially in a conservation area. Some may limit the placing of a wooden memorial to six months after burial, after which a more permanent memorial must be placed. Others may require stones of a certain shape or position to facilitate grass-cutting. Headstones of granite, marble and other kinds of stone are usually created, installed, and repaired by monumental masons. Cemeteries require regular inspection and maintenance, as stones may settle, topple and, on rare occasions, fall and injure people; or graves may simply become overgrown and their markers lost or vandalised.
Restoration is a specialized job for a monumental mason. Even overgrowth removal requires care to avoid damaging the carving. For example, ivy should only be cut at the base roots and left to naturally die off, never pulled off forcefully.
Many materials have been used as markers.

Stone
Fieldstones. In many cultures markers for graves other than enclosed areas, such as planted with characteristic plants particularly in northern Europe the yew, were natural fieldstones, some unmarked and others decorated or incised using a metal awl. Typical motifs for the carving included a symbol and the deceased's name and age.
Granite. Granite is a hard stone and requires skill to carve by hand. Modern methods of carving include using computer-controlled rotary bits and sandblasting over a rubber stencil. Leaving the letters, numbers and emblems exposed on the stone, the blaster can create virtually any kind of artwork or epitaph.
Marble and limestone. Both limestone and marble take carving well. Marble is a recrystallised form of limestone. The mild acid in rainwater can slowly dissolve marble and limestone over time, which can make inscriptions unreadable. Portland stone was a type of limestone commonly used in England – after weathering, fossiliferous deposits tend to appear on the surface. Marble became popular from the early 19th century, though its extra cost limited its appeal.
Sandstone. Sandstone is durable, yet soft enough to carve easily. Some sandstone markers are so well preserved that individual chisel marks are discernible, while others have delaminated and crumbled to dust. Delamination occurs when moisture gets between the layers of the sandstone. As it freezes and expands the layers flake off. In the 17th century, sandstone replaced field stones in Colonial America. Yorkstone was a common sandstone material used in England.
Slate. Slate can have a pleasing texture but is slightly porous and prone to delamination. Slate was commonly used by colonial New England carvers, especially in Boston where elaborate slate markers were shipped down the Atlantic coast as far south as Charleston and Savanah. It takes lettering well, often highlighted with white paint or gilding.
Schist. Schist Was a common material for grave making in the American Colonies during the 17th and 18th Century. While harder to Carve than Sandstone or Slate, lettering and symbols usually had to be carved deeper into the stone and therefore held up well over long periods of time.  While not as durable as most slate,  most have held up well against the elements.

Metal, wood and plants
Iron. Iron grave markers and decorations were popular during the Victorian era in the United Kingdom and elsewhere, often being produced by specialist foundries or the local blacksmith. Cast iron headstones have lasted for generations while wrought ironwork often only survives in a rusted or eroded state. In eastern Värmland, Sweden, iron crosses instead of stones have been popular since the 18th century.
White bronze. Actually sand cast zinc, but called white bronze for marketing purposes. Almost all, if not all, zinc grave markers were made by the Monumental Bronze Company of Bridgeport, CT, between 1874 and 1914.  The company set up subsidiaries in Detroit, Philadelphia, New Orleans, and Des Moines; a Chicago subsidiary was named the American Bronze Company, while the St. Thomas White Bronze Monument Company was set up in Ontario, Canada. They are in cemeteries of the period all across the U.S. and Canada. They were sold as more durable than marble, about 1/3 less expensive and progressive.
Wood. This was a popular material during the Georgian and Victorian era, and almost certainly before, in Great Britain and elsewhere. Some could be very ornate, although few survive beyond 50–100 years due to natural decomposition or termites and other wood boring insects.
Planting. Trees or shrubs, particularly roses, may be planted, especially to mark the location of ashes. This may be accompanied by a small inscribed metal or wooden marker.

Inscriptions
Markers sometimes bear inscriptions. The information on the headstone generally includes the name of the deceased and their date of birth and death. Such information can be useful to genealogists and local historians. Larger cemeteries may require a discreet reference code as well to help accurately fix the location for maintenance. The cemetery owner, church, or, as in the UK, national guidelines might encourage the use of 'tasteful' and accurate wording in inscriptions. The placement of inscriptions is traditionally placed on the forward-facing side of the memorial but can also be seen in some cases on the reverse and around the edges of the stone itself. Some families request that an inscription be made on the portion of the memorial that will be underground.In addition, some gravestones also bear epitaphs in praise of the deceased or quotations from religious texts, such as "requiescat in pace". In a few instances the inscription is in the form of a plea, admonishment, testament of faith, claim to fame or even a curse – William Shakespeare's inscription famously declares

Or a warning about mortality, such as this Persian poetry carved on an ancient tombstone in the Tajiki capital of Dushanbe.

Or a simpler warning of inevitability of death:

Headstone engravers faced their own "year 2000 problem" when still-living people, as many as 500,000 in the United States alone, pre-purchased headstones with pre-carved death years beginning with 19–.Bas-relief carvings of a religious nature or of a profile of the deceased can be seen on some headstones, especially up to the 19th century. Since the invention of photography, a gravestone might include a framed photograph or cameo of the deceased; photographic images or artwork (showing the loved one, or some other image relevant to their life, interests or achievements) are sometimes now engraved onto smooth stone surfaces.
Some headstones use lettering made of white metal fixed into the stone, which is easy to read but can be damaged by ivy or frost. Deep carvings on a hard-wearing stone may weather many centuries exposed in graveyards and still remain legible. Those fixed on the inside of churches, on the walls, or on the floor (often as near the altar as possible) may last much longer: such memorials were often embellished with a monumental brass.
The choice of language and/or script on gravestones has been studied by sociolinguists as indicators of language choices and language loyalty. For example, by studying cemeteries used by immigrant communities, some languages were found to be carved "long after the language ceased to be spoken" in the communities. In other cases, a language used in the inscription may indicate a religious affiliation.
Marker inscriptions have also been used for political purposes, such as the grave marker installed in January 2008 at Cave Hill Cemetery in Louisville, Kentucky by Mathew Prescott, an employee of PETA. The grave marker is located near the grave of KFC founder Harland Sanders and bears the acrostic message "KFC tortures birds". The group placed its grave marker to promote its contention that KFC is cruel to chickens.

Form and decoration
Gravestones may be simple upright slabs with semi-circular, rounded, gabled, pointed-arched, pedimental, square or other shaped tops. During the 18th century, they were often decorated with memento mori (symbolic reminders of death) such as skulls or winged skulls, winged cherub heads, heavenly crowns, or the picks and shovels of the gravedigger. Somewhat unusual were more elaborate allegorical figures, such as Old Father Time, or emblems of trade or status, or even some event from the life of the deceased (particularly how they died). Large tomb chests, false sarcophagi as the actual remains were in the earth below, or smaller coped chests were commonly used by the gentry as a means of commemorating a number of members of the same family. In the 19th century, headstone styles became very diverse, ranging from plain to highly decorated, and often using crosses on a base or other shapes differing from the traditional slab. By this time popular designs were shifting from symbols of death like Winged heads and Skulls to Urns and Willow trees. Marble also became overwhelmingly popular as a grave material during the 1800s in the United States.  More elaborately carved markers, such as crosses or angels also became popular during this time. Simple curb surrounds, sometimes filled with glass chippings, were popular during the mid-20th century.
Islamic headstones are traditionally more a rectangular upright shaft, often topped with a carved topknot symbolic of a turban; but in Western countries more local styles are often used.
Some form of simple decoration may be employed. Special emblems on tombstones indicate several familiar themes in many faiths. Some examples are:

Greek letters might also be used:

  
    
      
        α
        ω
      
    
    {\displaystyle \alpha \omega }
   (alpha and omega): The beginning and the end

  
    
      
        χ
        ρ
      
    
    {\displaystyle \chi \rho }
   (chi rho): The first letters spelling the name of Christ

Safety
Over time a headstone may settle or its fixings weaken. After several instances where unstable stones have fallen in dangerous circumstances, some burial authorities "topple test" headstones by firm pressure to check for stability. They may then tape them off or flatten them.
This procedure has proved controversial in the UK, where an authority's duty of care to protect visitors is complicated because it often does not have any ownership rights over the dangerous marker. Authorities that have knocked over stones during testing or have unilaterally lifted and laid flat any potentially hazardous stones have been criticised, after grieving relatives have discovered that their relative's marker has been moved. Since 2007 Consistory Court and local authority guidance now restricts the force used in a topple test and requires an authority to consult relatives before moving a stone. In addition, before laying a stone flat, it must be recorded for posterity.

Image gallery
See also
Gravestone rubbing
Khachkar
Mausoleum
Megalith
Murder stone
Sarcophagus
Scottish gravestones
The Devil's Chair (urban legend)
Tombstone tourist
Viewlogy

References
External links

In Search Of Gravestones Old And Curious by W.T. Vincent, 1896, from Project Gutenberg
Azeri.org, Sofi Hamid Cemetery (in Azerbaijani)
World Burial Index Archived 8 June 2010 at the Wayback Machine Photographs of memorial inscriptions plus free surname search
A Very Grave Matter Old New England gravestones
Historic Headstones Online Project to transcribe content from historic headstones
Pennsylvania German tombstones Archived 11 February 2021 at the Wayback Machine
Stockton University includes gravestone imagery in New Jersey
How to clean a Grave marker by Ralf Heckenbach
Stone Quarries and Beyond
"Memorializing the Civil War Dead:  Modernity and Corruption under the Grant Administration", by Bruce S. Elliott, in Markers XXVI, Association for Gravestone Studies, 2011, pp. 15–55.  (Reprinted with permission of the "Association for Gravestone Studies". (Details the beginning of the mass production of cemetery stones and the increased use of the sand blast process.)