GIF

GIF (Graphics Interchange Format) was introduced by the CompuServe online service in 1987, intended to provide a consistent and compact format for graphics to be downloaded on that service. Since the specifications were openly released, the format gained wide use in graphics software and on online services and bulletin board systems (BBSs), not just CompuServe.

In 1994, it became widely known that the format was encumbered by the use of the patent-protected LZW compression technology, which its owner, Unisys, was demanding licencing terms and royalties for certain sorts of uses. This made GIF a less-than-free format, spurring a desire on the part of some people for an unencumbered format, which led to the creation of the PNG format. However, it took several years for PNG to get widespread support in software, and in the meantime the World Wide Web experienced meteoric growth with GIF still used as the primary graphics format (alongside JPEG), though eventually PNG did become widespread on the Web as well. The patent in question expired in the US in 2003, and in other countries in 2004, so it is no longer an issue.

Unlike most other graphic formats, GIF supports multiple-frame animated graphics in addition to single-image graphics. These animated GIFs often turn up on the Web, though they are usually thought of as somewhat "retro" these days because they remind people of the excesses of the early wave of Web popularity when such tricks were common on pages on services such as GeoCities.