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. The defensive team is not privy to which type of play will develop. To protect against common plays, their line ends up divided up much the same way as the offense, with the defensive tackle at the front both holding the line as well as attempting to threaten the quarterback, the defensive backs positioned behind the line to protect against pass plays, and the linebackers positioned to counter a rush. Once the play starts, the defensive players tend to collapse towards the action, preventing forward motion of the rush, or blocking a pass. This commitment to a course of action is typically safe; there is only one forward pass allowed per play, so once the ball is passed the rushers are out of the action and all the defenders can attempt to block the receiver, and while anyone can throw the ball forward, doing so is so specialized that once the quarterback hands off the ball or tosses to a runner, the possibility of a forward pass is generally eliminated. Trick plays attempt to cause the defense to commit to a play in order to leave them badly out of position for the play that actually develops. A simple example is the end-around play, where one of the eligible receivers runs parallel to the line of scrimmage (see man-in-motion), takes the ball from the quarterback in a handoff or lateral toss, and then starts a rush. As the receiver would normally be expected to run down the field in order to catch a forward pass, the defensive back assigned to cover that motion starts opposite him some distance behind the line. If the back does not move laterally to match the motion of the receiver, the receiver may find themselves unopposed on the opposite side of the line once the play develops. More dangerous trick plays normally combine multiple passes or hand-offs than a single play. In the Flea Flicker, the ball is handed-off or laterally passed to a player in what appears to be