first-person shooter (played from the point of view of the shooter) electronic game released in 2001 by the Microsoft Corporation for its Xbox console (Xbox). Using state-of-the-art graphics, sophisticated genre improvements, and an array of weapons and vehicles, Halo's first release, Combat Evolved, was a resounding triumph that helped make the launch of the Xbox a success in the console gaming market.

In Halo, players control Master Chief, a super soldier who is trying to uncover the mystery of a strange object, the Halo. The majority of enemies a player encounters are a part of the Covenant, an alien race bent on destruction. The Covenant is broken up into several classes, which include grunts, elites, hunters, and jackals, all of which have certain tendencies, weaknesses, and strengths. Players also encounter the Flood, a parasitic alien that takes over human and Covenant soldiers and causes havoc. Gamers are often flanked by computer-controlled allies who provide cover fire and support in tough battles. By allowing players to use a variety of items and weaponry in different situations, Halo won fans with a system that was easy to learn but also skill-intensive enough to provide a challenge for veteran gamers.

Viewed as one of the most important video game releases in history, the first version of Halo sold more than five million copies. Halo spawned two sequels, Halo 2 and Halo 3, both of which were immensely popular. Multiplayer game play, a weak point of the first release, was greatly improved by Halo 2's inclusion on the Xbox Live online play network, which provided a dedicated server. Halo 3 continued the game's success, grossing more than $300 million in the first week of its release.