GIF
full spelling ： Graphic Interchange Format
GTF is a picture format developed to exchange pictures in an American personal computer communication network CompuServe. It is a standard format used on the Internet along with JPEG.
GIF format makes it possible to save pictures expressed with up to 256 colors. In other words, it is suitable for illustrations or icons that JPEG is not good at. There are several types of extension; an animation GIF, which can be used to save movies, a transparent GIF, which can be laid over background image by designating a transparent color, and an interlaced GIF, which can be opened before the whole picture is downloaded.
An algorithm LzW, which is used for compression, is patented by Unisys, so sales or deliveries of software that corresponds to GIF should be charged as a license fee for Unisys. Against this license fee, a license-free picture format called PNG is established.