It refers to a graphic that makes use of static images to create an animation effect and that uses GIF89a formatted files to do so.

A series of frames is what constitutes animated banners. Each of these frames is set a display time that is measured in terms of seconds. A loop is said to be complete when all images are run through in an animated sequence. There are various ways how animated GIF can be set to loop. They can either be set only once, for infinite period or anything in between. For buttons and animated banners GIF89a formats are generally used. These formats are supported by a number of browsers and are easy to work with. They however do lack in terms of functionality that is given by rich media.