In time for the holiday weekend, Computerworld has published a video gallery of ten Easter eggs in action.
The name "Easter egg" comes from the Easter tradition of hiding chocolate eggs for children to find. It has a similar meaning in software: an undocumented, hidden feature or message that users may stumble across.
The first software Easter egg is popularly thought to have occurred in 1979. In the early days of software development, programmer identities were jealously guarded. Software studios didn't want their staff to gain celebrity status, their names eclipsing those of the brands they'd created. Warren Robinett, then a programmer for Atari, didn't appreciate this lack of acknowledgement. He couldn't get his name in the manual for the Atari 2600 game Adventure — so he sneaked it into the game itself.