id Software was officially founded February 1, 1991 with the release of Commander Keen.
In 1992 Wolfenstein 3-D was released - a game that revolutionized the PC gaming industry.
id Software later produced the Doom and Quake series - games held in very high regard amongst the industry, gamers and modders alike.
id Software is also well known for their game engines. Their upcoming game, Rage, is built on the new 'id Tech 5, id have a history of open sourcing their old engines for developers to use.