Definition: In professional soccer there are two assistant referees whose job it is to call offsides, throw-ins and help the referee make decisions. Carrying a flag to signal their observations, linesmen must monitor the sidelines and goal lines and flag if the ball goes out of play, signalling which team the goal kick or throw-in should be awarded to.
A key aspect of their job is deciding whether a ball has crossed the goal line between the posts when the call is marginal.
Also Known As: Linesman.
