Overtime or extra time is an additional period of play specified under the rules of a sport to bring a game to a decision and avoid declaring the match a tie or draw where the scores are the same. In some sports, this extra period is played only if the game is required to have a clear winner, as in single-elimination tournaments where only one team or players can advance to the next round or win the tournament.

The rules of overtime or extra time vary between sports and even different competitions. Some may employ "sudden death", where the first player or team who scores immediately wins the game. In others, play continues until a specified time has elapsed, and only then is the winner declared. If the contest remains tied after the extra session, depending on the rules, the match may immediately end as a draw, additional periods may be played, or a different tiebreaking procedure such as a penalty shootout may be used instead.

The terms overtime and in overtime (abbreviated "OT" or "IOT") are primarily used in North America, whereas the terms extra time and after extra time (abbreviated "a.e.t.") are usually used in other continents.