The line of scrimmage in football is the yard line that shows the spot of the ball on the field. Wherever the ball goes, the line of scrimmage follows. Also known as the scrimmage line, the line of scrimmage is used to align players at the start of a down. The line of scrimmage can be seen as a blue line on television. A penalty called a false start will be called on a player that crosses the line of scrimmage prior to the snap.