Gif

"GIF" (graphics interchange format), is a bitmap image format  that was introduced by Steve Wihite of CompuServe in 1987 and has since come into widespread usage on the Internet due to its wide support and portability.

The GIF improved on black and white image transfers with 256 colors, while still retaining a compressed format that slow modems could load easily. Using the Graphics Control Extension (GCE), the GIF achieved animation via timed delays.

GIF images are compressed using the Lemo-Ziv-Welch (LZW) lossless data compression technique to reduce the file size without degrading the visual quality. This compression technique was patented in 1985. Controversy over the licensing agreement between the software patent holder, Unisys, and CompuServe in 1994 spurred the development of the Portablr Network Graphics (PNG) standard. By 2004 all the relevant patents had expired. 

http://mashable.com/2012/10/19/animated-gif-history/#v1.t_XUC4Gqo
 

http://m.instructables.com/id/How-to-Create-an-Animated-GIF-in-Photoshop-CS5/step4/Step-Four-How-to-Turn-Your-Brainbaby-into-a-GIF/