WAD is a file format used by FPS games that used the Doom game engine. Doom engine was developed for Doom I and Doom II computer games. WAD is a siple ZIP archive file.

WAD file stores game resources such as videos, textures, graphics, levels, maps, and additional information related to the game. WAD files can also be used for adding content to the game which expands its capabilites and features. WAD files were used by games such as Half Life, Quake, Hexen, and Heretic; rarely used nowadays.