加时赛是在比赛的常规时间中，为了在需要决出胜负的比赛中打破平局而进行的额外一段比赛。

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 most sports, this extra period is only played 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. In other sports, particularly those prominently played in North America where ties are generally disfavored, some form of overtime is employed for all games.