An end in American football is a player who lines up at either end of the line of scrimmage. Rules state that a legal offensive formation must always consist of seven players on the line of scrimmage. An end who lines up close to the offensive line is known as a tight end, while one who lines up some distance from the offensive line is known as a split end. In recent years, the generic term wide receiver has come to define both split ends and flankers (backs who line up in split positions but behind the line of scrimmage). The terms "split end" and "flanker" are no longer in common usage.
There is a commonly-used position on the defense called the defensive end. However, as there are no rules regulating the formation of the defense, players at this position commonly take on and share multiple roles with other positions in different defensive schemes.
Before the advent of two platoons, in which teams fielded distinct defensive and offensive units, players that lined up on the ends of the line on both offense and defense were referred to simply as "ends".