First-person shooter

First-person shooters are a genre of video game. You play looking from the character's eyes, I.E. from the first-person perspective, whomever that may be.

History
The first person shooter that brought it into the world was the game Battlezone, although the first game to make it truly popular was ID Software's Wolfenstein 3D.

ID Software's next game, Doom truly established the genre, with it's many evolutionary leaps forward, including the ability for players to move in three axes via stairs and the and with it's inclusion of multiplayer modes, allowing players to play with or against each other over a distance for the first time.

Halo: Combat Evolved, Halo 2, and Halo 3 are also first-person shooters, although when you enter vehicles or turrets the view changes to third-person.

First-Person in Halo
The first Halo game introduced few changes to the idea of a first person shooter. However Halo 2 introduced an interesting aspect never before seen: The character's own body. In most other first person shooters, when the character looks down they see only a shadow below them, as though they are a magical head and gun floating throughout the levels. However in Halo 2 when the character looks down, they see their own body. Characters are able to see themselves run, jump, stand or even stick a Plasma Grenade to their feet because their body exists in real-time during the game.

First-Person in Vehicles
There are two incidences where first-person-view can be obtained in vehicles. In Halo: Combat Evolved if you play on co-op with another person, and recently on a Hornet in Halo 3.

On co-op Halo 1, if one player gets in a Scorpian the driver will normally have third-person-view, but if another player rides alongside on the Scorpian (the passenger), the second player will have first-person-view, unlike other vehicles like the Warthog where it only shows third-person-view on the passenger side.

The other incident is where a player boards a Hornet in Halo 3 while another player is piloting. The passenger will see everything in first-person-view. When viewed in Theater Mode, if the camera is fixed on the passsger's view, the video will even show the passenger's first-person-view perspective. However, if the camera is moved, it would show third-person-view normally like in other vehicles. Before, passenger's could only see from a third-person-perspective, but recently every passenger that boards a Hornet will be able to see in first-person-view. Note: this does not work in any other vehicle that has a passenger seat. Whether a glitch, an update, or whatever, players can now see in first-person-view only on the passenger side of a Hornet.