What is the GIF graphics file format?

The Graphical Interchange Format (GIF) is one of the most widely used image formats on the web. GIF files are recognizable by their .gif file extension. GIF is suitable for images with sharp edges and relatively few gradations of color, such as line art, cartoons, and text. You can also create background transparencies and animations using GIF images.

History of GIF

In 1987, CompuServe Corporation created the GIF file format to be used for the storage and online retrieval of bitmapped graphical data. The GIF specification required the use of the LZW algorithm to compress the data stored in each GIF file. In 1984, while working for Sperry Corporation (now Unisys), Terry Welch modified the Lempel-Ziv 78 (LZ78) compression algorithm for greater efficiency for implementation in high-performance disk controllers. The result was the LZW algorithm.

Although GIF itself was released as a free and open specification, Unisys maintained a patent for LZW compression in some countries until summer 2004. (These patents have expired; Unisys now holds and has patents pending on improvements to LZW compression.) In the 1990s (before the LZW US patent expired), developers concerned about patent enforcement devised the PNG format, intended as a patent-free replacement for GIF. For information about the LZW patent, see:

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