Lined up about 10–15 yards from the line of scrimmage in the defensive backfield, safeties defend against the pass, provide support on rushing plays and occasionally rush into the offensive backfield to disrupt the play.

Standard defenses feature two types of safeties:

• A free safety usually lines up farther away from the line of scrimmage and follows the ball, reacting to what the quarterback does. He is “free” to double cover another player and help the cornerback if needed.
• A strong safety typically lines up closer to the line of scrimmage opposite the “strong side" of the offense — the side on which the tight end lines up. He helps on passing plays and supports his teammates on rushing plays.