a.k.a. GIF89a/GIF animation -or- Multi Block GIF
(pronounced: giff or jiff)
A type of GIF format that allows a series of static images to be displayed one after another or on top of each other, giving the effect of motion or animation. Since their implementation in Netscape Navigator 2.0, animated GIFs have been one of the easiest ways to put animation and movement on Web pages. Animated GIFs have been around since the introduction of the GIF89a format in 1989, but they didn't appear on the Web at that time because Web browsers initially did not support GIF89a's animation features.
Historical perspective: In early 2012, PBS released a mini-documentary about animated GIFs, watch it here!
NetLingo Classification: Net Programming