In team sports, substitution (or interchange) is replacing one player with another during a match. Substitute players that are not in the starting lineup (also known as bench players, backups, interchange, or reserves) reside on the bench and are available to substitute for a starter. Later in the match, that substitute may be substituted for by another substitute or by a starter who is currently on the bench. Free substitution or rolling substitution is a rule in some sports that allows players to enter and leave the game for other players many times during the course of a game, generally during a time-out or other break in live play; and for coaches to bring in and take out players an unlimited number of times. In other sports, limited substitution restricts the manner in which players can be replaced.

Sports that allow free substitution

Sports that allow unlimited substitution during live play

Sports that allow unlimited substitutions during stoppages of play only

Sports with limited substitution

Sports that allow a limited number of substitutions

Sports that only allow substitution to replace injured players

Sports with mixed or hybrid systems