Encroachment in football is a penalty that is called on the defensive team when a defensive player illegally crosses the line of scrimmage before the snap and makes contact with an opposing player or has a clear path towards the quarterback. This penalty results in a loss of five yards for the defense.
Offsides occurs when a defensive player is on or over the line of scrimmage when the ball is snapped. Encroachment occurs only before the snap. Also, encroachment only occurs when a defensive player makes contact with an offensive player.
The neutral zone infraction penalty is most similar to encroachment, but again, encroachment only occurs when contact is made to an offensive player. A neutral zone infraction may be called if a defensive player enters the neutral zone (over the line of scrimmage) without touching an offensive player.
The encroachment penalty occurs before the play begins. That is important information because, unlike an offsides penalty, the offense cannot get a free play. With an offsides penalty, the offense may run continue to run the play and then get the option to keep the outcome or take the penalty. With encroachment, the play is whistled dead as soon as the infraction occurs.
As stated above, the penalty results in the offense gaining 5 yards. The offense, however, does not get an automatic first down, as is the case with some penalties. A first down only occurs If the 5 yards is enough to reach the yards to go. Players may also commit encroachment penalties without ever receiving an individual punishment such as ejection.
In high school, encroachment is called anytime a defender crosses the line of scrimmage before the snap, whether there is contact or not. A neutral zone infraction is never called in high school football.