Pass interference is a penalty in American football that occurs when a player impedes another player's ability to catch a thrown ball. This can happen when a defensive player makes illegal contact with a receiver before the ball arrives, or when an offensive player pushes off a defender to create space. The penalty can result in a significant advantage for the team that was fouled. If the interference occurs during a pass play, the offended team is awarded a first down at the spot of the foul, or if it occurs in the end zone, they may receive a penalty at the one-yard line.