What does the running back do?

Answer 1

the running back is a pretty vital position. his job is to carry the football up the field on offense by taking either a hand off or a toss from the quarterback behind the line of scrimmage. He offers an alternative to passing. Notable examples include Ladanian Tomlinson, Adrian Peterson, Brandon Jacobs, Deuce McAlister, etc. The running back also can be sent out on passing routes as a receiver, or can stay back to block any defenders that may try to get the QB or as a blocker for the fullback/recievers.

Answer 2

Runs through the line of scrimmage (line of the players) or gets the football and runs outside the line of scrimmage.