An animated GIF, also known as a GIF animation, is a digital image in the GIF image file format that makes use of this format's feature to display animations.
The animations are usually cyclic animations and rarely more than 10 frames or so. They are very popular on the Web because every graphical Web browser can natively play GIF animations, and they are comparatively easy to create.
For longer and smoother animations, Flash is a better format, but requires a browser plug-in. For video-quality animations with sound, a video file format is the best choice.