Editing GIF (section)

==History==
{{Further|GIF#Unisys and LZW patent enforcement|label1=§ Unisys and LZW patent enforcement}}
[[File:Under-Construction-Bulldozer.gif|thumb|"Under construction" animated GIFs were a common feature of unfinished websites in the late 90s and early noughts.]]
[[File:Eokxd.gif|thumb|Animated GIFs like this one were once a common decorative feature of personal websites in the late 90s and early noughts.]]
[[CompuServe]] introduced GIF on 15 June 1987 to provide a color image format for their file downloading areas. This replaced their earlier [[run-length encoding]] format, which was black and white only. GIF became popular because it used [[Lempel–Ziv–Welch]] [[data compression]]. Since this was more efficient than the run-length encoding used by [[PCX]] and [[MacPaint]], fairly large images could be downloaded reasonably quickly even with slow [[modem]]s.

The original version of GIF was called 87a.<ref name="87aSpec" /> This version already supported multiple images in a stream.

In 1989, CompuServe released an enhanced version, called 89a,<ref name="89aSpec" /> This version added:
* support for animation delays
* [[Transparency (graphic)|transparent]] background colors
* storage of application-specific metadata
* allowing text labels as text (not embedding them in the graphical data). As there is little control over display fonts, however, this feature is rarely used.

The two versions can be distinguished by looking at the first six [[byte]]s of the file (the "[[magic number (programming)|magic number]]" or signature), which, when interpreted as [[ASCII]], read "GIF87a" or "GIF89a", respectively.

CompuServe encouraged the adoption of GIF by providing downloadable conversion utilities for many computers. By December 1987, for example, an [[Apple IIGS]] user could view pictures created on an [[Atari ST]] or [[Commodore 64]].<ref name="caa198712">{{cite news | url=https://archive.org/stream/COMPUTEs_Apple_Applications_Vol._5_No._2_Issue_6_1987-12_COMPUTE_Publications_US#page/n11/mode/2up | title=Online Art | work=Compute!'s Apple Applications | date=December 1987 | access-date=14 September 2016 | pages=10}}</ref> GIF was one of the first two image formats commonly used on Web sites, the other being the black-and-white [[XBM]].<ref>{{Cite book|title=Ajax: The Definitive Guide: Interactive Applications for the Web|last=Holdener III|first=Anthony|publisher=O'Reilly Media|year=2008|isbn=978-0596528386}}</ref>

In September 1995 [[Netscape (web browser)#Release history|Netscape Navigator]] 2.0 added [[#Animated GIF|the ability for animated GIFs to loop]].

While GIF was developed by [[CompuServe]], it used the [[Lempel–Ziv–Welch]] (LZW) [[lossless data compression]] algorithm patented by [[Unisys]] in 1985. Controversy over the licensing agreement between [[Unisys]] and [[CompuServe]] in 1994 spurred the development of the [[Portable Network Graphics]] (PNG) standard. In 2004, all patents relating to the proprietary compression used for GIF expired.

The feature of storing multiple images in one file, accompanied by control data, is used extensively on the Web to produce simple [[computer animation|animations]]. 

The optional [[Interlacing (bitmaps)|interlacing]] feature, which stores image scan lines out of order in such a fashion that even a partially downloaded image was somewhat recognizable, also helped GIF's popularity,<ref>{{Cite book|title=Encyclopedia of Multimedia|last=Furht|first=Borko|publisher=Springer|year=2008|isbn=978-0387747248}}</ref> as a user could abort the download if it was not what was required.

In May 2015 [[Facebook]] added support for GIF.<ref>{{cite magazine |url=https://www.wired.com/2015/05/real-gif-posting-on-facebook/ |title=You Can Finally, Actually, Really, Truly Post GIFs on Facebook |magazine=[[Wired (magazine)|Wired]] |first=Molly |last=McHugh |date=2015-05-29 |access-date=2015-05-29 |archive-date=30 May 2015 |archive-url=https://web.archive.org/web/20150530004146/http://www.wired.com/2015/05/real-gif-posting-on-facebook/ |url-status=live }}</ref><ref>{{cite web |url=https://techcrunch.com/2015/05/29/facebook-confirms-it-will-officially-support-gifs |title=Facebook Confirms It Will Officially Support GIFs |date=2015-05-29 |access-date=2015-05-29 |first=Sarah |last=Perez |publisher=[[TechCrunch]] |archive-date=30 May 2015 |archive-url=https://web.archive.org/web/20150530043012/http://techcrunch.com/2015/05/29/facebook-confirms-it-will-officially-support-gifs/ |url-status=live }}</ref> In 2014, [[Twitter]], also added support to GIF as well as  [[Instagram]] in 2018. <ref>{{Cite web|url=https://instagram-press.com/blog/2018/01/23/introducing-gif-stickers/|title=Introducing GIF Stickers|date=2018-01-23|website=Instagram|language=en-US|access-date=2019-09-19|archive-date=12 December 2019|archive-url=https://web.archive.org/web/20191212103358/https://instagram-press.com/blog/2018/01/23/introducing-gif-stickers/|url-status=live}}</ref>

In 2016, the Internet Archive released a searchable library of GIFs from their [[GeoCities|Geocities]] archive.<ref>{{Cite web |last=Ghoshal |first=Abhimanyu |date=2016-10-28 |title=Enjoy 1.6 million gloriously old-school GIFs from the GeoCities era |url=https://thenextweb.com/news/you-can-now-enjoy-1-6-million-gloriously-old-school-gifs-from-the-geocities-era |access-date=2024-11-04 |website=TNW {{!}} Shareables |language=en}}</ref><ref>{{Cite web |title=GifCities |url=https://gifcities.org/ |access-date=2024-11-04 |website=gifcities.org}}</ref>