Regulation football fieldsÂ used by the National Football League and the National Collegiate Athletic Association are 120 yards long and 53 yards wide. The field is rectangular, and 100 yards are considered to be in play with end zones on either end of the field that are 10 yards long.
A football field is marked with yard lines every 5 yards starting at either end zone line. If a player crosses either of the sidelines with the ball, he is considered to be out of bounds and the next play begins where the ball went out of bounds. Touchdowns are scored when any part of the ball, in possession of a player, crosses the specified end zone line.