Encroachment

In gridiron football, encroachment refers to when before the snap, a defensive player illegally crosses the line of scrimmage and makes contact with an opponent or has a clear path to the quarterback. In high school, this includes any crossing of the neutral zone by the defense, whether contact is made or not. It is a violation of the game's code. It is similar to offside except when it occurs, the play is not allowed to begin. Like offside violations, the violating team is penalized 5 yards.

The head linesman has the duty of watching out for encroachment and other similar infractions, and the line judge assists in this process.

SPORTS

American Football

Game play in American football consists of a series of downs, individual plays of short duration, outside of which the ball is dead or not in play. These can be plays from scrimmage – passes, runs, punts, or field goal attempts (from either a place kick or a drop kick) – or free kicks such as kickoffs and fair catch kicks. Substitutions can be made between downs, which allows for a great deal of specialization as coaches choose the players best suited for each particular situation. During a play, each team should have no more than 11 players on the field, and each of them has specific tasks assigned for that specific play.