A GIF (the original and preferred pronunciation is DJIF) is one of the two most common file formats for graphic images on the World Wide Web. The other is the JPEG.

On the Web and elsewhere on the Internet (for example, bulletin board services), the GIF has become a de facto standard form of image. The format is actually owned by Compuserve (now part of AOL) and companies that make products that exploit the format (but not ordinary Web users or businesses that include GIFs in their pages) need to license its use.

Technically, a GIF uses the 2D raster data type, is encoded in binary, and uses LZW compression. There are two versions of the format, 87a and 89a. Version 89a (July, 1989) allows for the possibility of an animated GIF, which is a short sequence of images within a single GIF file. A GIF89a can also be specified for interlaced presentation.

A patent-free replacement for the GIF, the PNG format, has been developed by an Internet committee and major browsers support it or soon will.