An incomplete forward pass in football is a pass attempt in which the ball is not caught and falls to the ground. An incomplete pass results in no yardage being gained by the offense and the next play continues from the same spot as the previous play that resulted in an incompletion.
A forward pass is essentially a regular pass, with the quarterback throwing the ball past the line of scrimmage in an effort to complete a pass to a receiver. In order to be considered a legal pass, the ball must travel forwards past the spot where the ball was hiked.
An incompletion results when neither the receiver or the defender is able to catch the ball. A catch by the receiver means there has been a completed pass, while a catch by the defender results in an interception. Once the ball falls to the ground, it is considered a "dead ball" and cannot be picked up or advanced by any member of the offense or the defense.
The following plays constitute an incompletion:
Incomplete passes factor greatly into a very important statistic for quarterbacks, known as completion percentage. The best quarterbacks tend to have a high completion percentage, meaning they consistently throw catchable balls that the receivers can catch and advance up the field to help the offense score. Low completion percentages generally reflect poor throws and subpar decision-making skills by the quarterback, resulting in no yardage gained for the offense on passing plays a vast majority of the time.