Safety ( American and Canadian football position ) Safety ( S ) is a position in American and Canadian football , played by a member of the defense . The safeties are defensive back s who line up from ten to fifteen yards behind the line of scrimmage . There are two variations of the position in a typical formation , the free safety ( FS ) and the strong safety ( SS ) . Their duties depend on the defensive scheme . The defensive responsibilities of the safety and cornerback usually involve pass coverage towards the middle and sidelines of the field , respectively . Safeties are the last line of defense , and are thus expected to be sure tacklers . As professional and college football have become more focused on the passing game , safeties have become more involved in covering the eligible pass receivers . Strong safety . The strong safety tends to be somewhat larger and stronger than the free safety . However , the word " strong " is used because he is assigned to cover the " strong side " of the offense , the side on which the big , powerful tight end lines up on offensive plays . The strong safety tends to play closer to the line and assist in stopping the run . He may also be responsible for covering a player , such as a running back or fullback or H - back , who comes out of the backfield to receive a pass . A strong safety ' s duties are a hybrid of those belonging to a linebacker and those of the other defensive backs , in that he both covers the pass and stops the run . Two of the most notable retired strong safeties are Ken Houston and John Lynch . Among the best active strong safeties are Troy Polamalu and Adrian Wilson . Free safety . The free safety tends to be smaller and faster than the strong safety . His job tends to be to keep some distance from the line of scrimmage , watch the play unfold , and follow the ball . The free safety would correspond to the quarterback in man coverage , but as the quarterback usually remains in the pocket the free safety is " free " to double cover another player . On pass plays , the free safety is expected to assist the cornerback on his side and to close the distance to the receiver by the time the ball reaches him . Offenses tend to use the play - action pass specifically to make the free safety expect a run play , which would draw him closer to the line of scrimmage , and reduce his effectiveness as a pass defender . Furthermore , quarterbacks often use a technique to " look off " a free safety , by purposely looking to the other side of the field during a pass play , with the intention to lure the free safety away from the intended target receiver on the other side of the field . This phenomenon often tests how effective a free safety ' s wit and athleticism is at defending long pass plays . If the offense puts a receiver in the slot , then the free safety may be called upon to cover that receiver . Free safeties occasionally blitz as well . When this happens , the pressure on the quarterback is often very severe since a blitz by a defensive back is not usually anticipated . Free safeties , because of their speed and deep coverage , are often prone to catching interceptions . Standout retired free safeties include Paul Krause , Larry Wilson , and Willie Wood . Ed Reed and Nick Collins are the most notable currently active free safeties . Cover - 2 . Instead of the safeties dividing up their jobs in terms of run support and pass support , the safeties will sometimes divide up the field into a left half and a right half , with each being responsible for anything that comes into his half of the field . This type of division of responsibility is becoming increasingly common , and is called a " cover - 2 " defense . The cover - 2 was first used by the Pittsburgh Steelers in the 1970s , but was made famous by the Tampa Bay Buccaneers of the late 1990s . Led by head coach Tony Dungy and defensive coordinator Monte Kiffin , the Buccaneers built a dominating defense , with strong safety John Lynch at the forefront . This particular variation of the cover - 2 is referred to as the " Tampa 2 " . Since then , the popularity of the cover - 2 has soared . Both of the teams in Super Bowl XLI , the Colts and the Bears ( the former being coached by Dungy , the latter by his former protégé at Tampa , Lovie Smith ) , ran a base cover - two defense .