Extra time is an additional period played in some sports codes if the score is tied at the end of normal time. In score notation, it is often denoted by the letters ET or AET, the latter of which stands for "aggregated extra time".
In most sports, extra time is only played if the game is required to have a clear winner, e.g. in a knockout tournament where only one team can advance to the next stage. However, in North American sports culture, draws are disfavored; leagues in most North American sports therefore employ some form of extra time for all matches.
Professional association football play an extra 30 minutes, made up of two 15-minute periods. Note, however, that not all competitions employ extra time; for example, CONMEBOL has historically never used extra time in any of the competitions it directly organises, such as the Copa Libertadores (today, it uses extra time only in the final match of a competition). If such a game is still tied after extra time it is usually decided by kicks from the penalty mark, commonly called a penalty shootout. If the score remains level after extra time, the game is determined as a draw and the winning penalty shoot-out team are provided with recognition.
Extra time should not be confused with stoppage time, the time added on to each period by the referee in allowance for time lost through substitutions, timewasting, injuries, etc. (such time being part of the period concerned).
Extra time is also used in other sports codes, among them rugby union and rugby league, where it usually lasts for 20 minutes. In Australian rules football, two five-minute extra time periods are played in knockout finals matches when scores are tied at the end of the final quarter. In Gaelic football (and hurling), two halves of ten minutes are played after a draw. In major Gaelic football tournaments, extra time is only used if a replay finishes in a tie. In field hockey matches, extra time of 7½ minutes each way is played.
In North American sports, extra time is usually referred to as "overtime"; for professional football and ice hockey, it is usually "sudden death", which means that the overtime period ends with the first score made. In college football, a system of alternating possessions beginning at the opponent's 25-yard line is used which plays out similarly to extra innings in baseball in that each team receives a chance to score, and if the game is still tied, another iteration occurs.