An animated GIF (Graphics Interchange Format) file is a graphic image on a Web page that moves - for example, a twirling icon or a banner with a hand that waves or letters that magically get larger. In particular, an animated GIF is a file in the Graphics Interchange Format specified as GIF89a that contains within the single file a set of images that are presented in a specified order. An animated GIF can loop endlessly (and it appears as though your document never finishes arriving) or it can present one or a few sequences and then stop the animation. Animated GIFs are frequently used in Web ad banners.
Java, Flash, and other tools can be used to achieve the same effects as an animated GIF. However, animated GIFs are generally easier to create than comparable images with Java or Flash and usually smaller in size and thus faster to display.