Reputation

Reputation is the opinion of the public toward a person or a group of people.

Fallout
Reputation in Fallout can be considered the equivalent of Karma from Fallout 2.

Besides global reputation, the character can be endowed with various reputation perks.

Fallout 2
Reputation in Fallout 2 is a way to measure general feeling for your character in each of the towns you visit. Reputation can be modified by doing good or bad deeds, like completing quests or killing townsfolk.

Fallout: New Vegas
In Fallout: New Vegas, your reputation among various factions will be tracked, and will even give you access to new areas in the game.