When one player is replaced by another during a game, this is called a “substitution”. Depending on the league, the number of substitutions is limited per game. Once a player on the bench crosses in front of the 10 ft line, they have entered the substitution zone and must be subbed in. Players are to wait, one inside the court and one outside the court, in front of the 10 ft line until signaled by the bookkeeper to switch.