In 1987 CompuServe released the Graphics Interchange Format (GIF) standard as a new format to save and retrieve computer-based images.
The GIF format supports up to 8 bits per pixel, allowing a single image to reference a palette of up to 256 distinct colors. The colors are chosen from the 24-bit RGB color space. It also supports animations and allows a separate palette of 256 colors for each frame.
Learn more at http://en.wikipedia.org/wiki/Graphics_Interchange_Format