A save occurs when a relief pitcher, non starter, does one of the three things:
1. He comes into the game with a lead of no more than three runs and pitches for at least one full inning, to end the game.
2. He comes into the game with the potential tying run either on base, at bat, or on deck.
3. He pitches "effectively" (usually for at least three innings) after entering the game with a lead.