The neutral zone in football is an imaginary area of the field that is only used in dead ball situations, such as before the ball is snapped or kicked. The neutral zone separates the offense and defense and is present before every down. It runs the entire length of the field parallel to the end zones, and is the same width as the football. Each end of the neutral zone is made up of the line of scrimmage which restricts either the offense or defense.
In the NFL, the neutral zone is often referred to synonymously with the line of scrimmage because its width is so short. No players on either the offense or defense are allowed to enter the neutral zone before the ball is snapped, except for the center (C) on offense who is responsible for snapping the ball. On televised football games, the neutral zone or line of scrimmage is usually marked by an imaginary yellow or blue line.
For kickoffs, some changes occur to the neutral zone. The width of the neutral zone increases to 10 yards in order to keep both teams separated, while the length remains the full length across the field. Only a kicker and holder are allowed to enter the neutral zone for kicking plays. Additionally, the kicking team may not touch the ball until it has crossed the neutral zone or a player on the opposing team has touched it.
The neutral zone is a very important part of the field and has various rules and regulations. First, at the start of every down there must be at least 7 offensive players lined up on their side of the neutral zone (line of scrimmage) prior to the snap.
There are also a number of penalties associated with the neutral zone in football. A neutral zone infraction penalty occurs when a defensive player moves into the neutral zone and forces an offensive player to move as a result. This penalty is a loss of 5 yards for the defense. A very similar penalty is encroachment, which is called when a member of the defense crosses the neutral zone and makes contact with a player on the offense before the ball is snapped. This is also a 5 yard penalty.
Finally, an offsides penalty occurs when any part of a player is within or on the wrong side of the neutral zone at the same time as the ball is snapped, causing a loss of 5 yards.