When discussing the passing game in American football, you use certain words and descriptions. Because passing involves the quarterback throwing the football, many of these terms relate to preventing or trying to prevent a receiver from catching that pass:
Deflection: A deflection happens when a defensive player uses his hands or arms to knock down (or deflect) a pass before it reaches the receiver. This act usually occurs near the line of scrimmage when defensive linemen jump, arms raised, into a quarterback’s visual passing lane, hoping to deflect the pass. Deflections can lead to an interception or incompletion.
Holding: Holding is the most common penalty called against the offense when it’s attempting to pass. The offense receives a 10-yard penalty (and repeat of down) when any offensive player holds a defensive player by grabbing his jersey or locking his arm onto the defensive player’s arm while that player is trying to sack the quarterback. This penalty is also known as illegal use of the hands, arms, or any part of the body.
Illegal forward pass: A quarterback can’t cross the line of scrimmage and throw the ball. This penalty often occurs when the quarterback runs forward, attempting to evade defensive players, and forgets where the line of scrimmage is. The offense is penalized 5 yards from the spot of the foul and loses a down.
Intentional grounding: This penalty occurs when a quarterback standing in the pocket deliberately throws the ball out of bounds or into the ground. It can be interpreted in the following three ways, with the first two drastically penalizing the offense:
No. 1: The quarterback is attempting to pass from his own end zone and, prior to being tackled, intentionally grounds the ball, throwing it out of bounds or into the ground. The defense is awarded a safety, worth two points, and the offense loses possession of the ball and has to kick the ball from its own 20-yard line. (NFL teams usually kick off from the 30-yard line.)
No. 2: The quarterback is trapped more than 10 yards behind his own line of scrimmage and intentionally grounds the ball for fear of being tackled for a loss. This penalty is a loss of down, and the ball is placed at the spot of the foul, which in this case is where the quarterback was standing when he grounded the ball. Otherwise, the intentional grounding penalty calls for loss of down and 10 yards.
No. 3: The quarterback steps back from the center and immediately throws the ball into the ground, intentionally grounding it. This play is common when an offense wants to stop the clock because it either wants to preserve its timeouts or is out of timeouts. For this type of intentional grounding, the penalty is simply a loss of a down.
Interception: An interception is the act of any defensive player catching a pass. Along with a fumble, an interception is the worst thing that can happen to a quarterback and his team. It’s called a turnover because the defensive team gains possession of the ball and is allowed to run with the ball in an attempt to score.
Roughing the passer: This penalty was devised to protect the quarterback from injury. After the ball leaves the quarterback’s hand, any defensive player must attempt to avoid contact with him. Because a defensive player’s momentum may cause him to inadvertently run into the quarterback, he’s allowed to take one step after he realizes that the ball has been released. But if he hits the quarterback on his second step, knowing that the ball is gone, the referee (the official standing near the quarterback) can call roughing. It’s a 15-yard penalty against the defense and an automatic first down.
This penalty is difficult to call unless the defensive player clearly hits the quarterback well after the quarterback releases the ball. After all, it’s pretty tough for defensive ends, who are usually over 6 feet and weigh 250 pounds, to come to an abrupt stop from a full sprint.
Sack: A sack happens when the quarterback is tackled behind the line of scrimmage by any defensive player.
Trapping: Receivers are asked to make a lot of difficult catches, but this one is never allowed. Trapping is when a receiver uses the ground to help him catch a pass that’s thrown on a low trajectory. For an official to not rule a reception a trap, the receiver must make sure either his hands or his arms are between the ball and the ground when he makes a legal catch. Often, this play occurs so quickly, only instant replay can show that the receiver wasn’t in possession of the ball — instead it shows that he trapped it.