What is an assistant referee?

Assistant referees, formerly known as linesmen, are officials in football (soccer) matches who support the main referee in enforcing the rules of the game. Their primary duties include indicating when the ball has left the field of play, signaling offside offenses, and assisting with other decisions such as substitutions or fouls near their touchline. Assistant referees use flags to communicate their observations to the main referee, helping ensure fairness and accuracy throughout the match.