The main purpose of this unit is to protect the quarterback or the running back by blocking the defenders. The offensive line has 5 men lined up. The center snaps the ball to the quarterback and is in the middle of all the men. The two guards are on both sides of the center. On the sides of the guards are the two tackles. The offensive line has numbers between 60 up to 79. Also tight ends can also join in some cases to help block or to catch a pass. Tight ends have the same numbers as a wide receiver.