Due to a variety of interacting rules, offensive plays generally fall into two distinct groups. Plays where the (planned) source of gains are through the quarterback throwing the ball forward are known as "passing plays", while those where the gains are due to the player running with the ball are "rushing plays". Rules governing which players are eligible to receive a pass results in the offensive team being split into groups; the guards protect the quarterback, wide receivers and tight-ends are positioned at the line to run forward to receive passes, and the backs are positioned behind the line to receive the ball in a hand-off and then continue running forward for a rush.