Safety

Safety (S) is a defensive position, played in the backfield, 15 yards behind the line of scrimmage.

Responsibility
The main responsibility is to prevent anyone from passing. There is an 80% chance that if the offense passes the Safety, they will score a touchdown. During a Passing Play, Safety's make sure no one is open at any time to receive the ball. They have the same job as Cornerback, but only 15 yards back (depending on the play). Safety also tries to prevent the Running Back from passing by, IF it is a running play. During a Running Play, Safety helps out the Cornerback who is getting blocked by the Wide Receiver. If the Cornerback fails to tackle the Runner (generally a Running Back), it is now up to the Safety to make a good tackle on him. If safety misses, it is likely they will make a touchdown, or at least get to 1st down.