A keyboard or game pad button sequence that gives the player an advantage in
the game. For example, you may have a cheat code to give your character infinite
health, walk through walls, skip a level, or even 'god mode' where your
character can't die. Codes are initially used by developers and
beta testers to
test specific aspects and functions in a game and cheat modes are often left in
the finished game product.
All About Multiplayer PC Gaming in Webopedia's "Did
You Know...?" section.