For application-specific terms, refer to the help feature of that application.

GIF

Graphics Interchange Format. A bitmap file format that uses lossless compression and supports 256 colors, transparency, interlacing, and animation. It is the most common format for graphics on the web. See PNG, JPEG, Lossless Compression, Bitmap Graphic, Animated GIF.

GUI

Graphical User Interface. A program interface that takes advantage of the computer's graphic capabilities to make the program easier to use. See Interface.