Karma is a game mechanic measured in points. Classified by three types, good, neutral, and evil, the player character always start a new game with 0 Karma points, which is considered neutral. Wasteland inhabitants will behave differently toward the player character depending upon Karma, and it serves as a factor in unlocking certain dialogue options and game endings. Some games use both Karma and reputation as mechanics, while others use one or the other.
In Fallout 2, "general reputation" is renamed to Karma, reputation titles are kept and a new stat called "Reputation" is added, acting as a measurement of how one is perceived in specific locations or among certain groups.
In Fallout 3, although Karma is measured in points, only associated status and titles appear.