A returner is a player on the special teams who performs returns. There are a few types of returners:
On a return, the returner's responsibilities are:
A return is when a returner catches the ball from a kickoff or punt and runs with it on the field toward the opposing team's end zone. The return determines the initial scrimmage line for the offensive drive.
On a touchdown return the returner scores a touchdown when making the return on a kickoff or punt. Touchdown returns are very rare and hard to do.
Field position in football describes the location of the ball in relation to the end zones. On a return, a returner should bring the ball into the red zone if he can.
A fair catch is a signal the returner can make while the ball is in flight on a return to ask for an unhindered attempt at catching the ball.
A touchback is a signal the returner can make in the end zone by dropping down on one knee when catching the kickoff or punt. Touchbacks place the scrimmage line on the 20-yard line.