Slotback

Slotback, sometimes referred to as an S-back or A-back, is a position in gridiron football. The "slot" is the area between the offensive tackle and the wide receiver. A player who lines up between those two players and behind the line of scrimmage fills that "slot".

The slotback position is a fixture of Canadian football and indoor football where they act as extra receivers. It is also used in American football where the position requires a versatile player who must combine the receiving skills of a wide receiver, the ball-carrying skills of a running back, and the blocking skills of a tight end.

Slotbacks are often as many as five yards behind the line of scrimmage when the ball is snapped. In both the Canadian and indoor game, slotbacks can make a running start toward the line of scrimmage before the snap. In most forms of American football this would be called illegal motion, although a few professional leagues such as the World Football League, and XFL allowed forward motion. In modern NFL, the slotback is often referred to as the "flex" position.