'The Graphics Interchange Format (or GIF for short) has long been one of the most popular image formats among computer users and programmers.
The main types of GIF images are 87a and 89a. 87a is a simpler type of image and has support for only one stationary picture. 89a however, supports multiple images, which can be compressed into a single GIF file. These images then can be strung together to create a crude "slideshow" animation, called an animated GIF or anigif.
The quality of GIF images has greatly improved as the format has evolved. While the initial GIF files only had support for 256 colors, advanced blending and transparency techniques have made it so that more colors can be created.'