Illegal motion (5 yards) - Only players in the backfield are permitted to move. They must either travel parallel to the line of scrimmage or be placed before the play. When the ball is snapped, they cannot be traveling toward the line of scrimmage. Too many guys on the move (5 yards): Two players cannot move at the same time. They can cross paths and then break away from each other, but only one of them can advance more than 5 yards downfield first.
The primary purpose of illegal motion is to provide a different look to the defense. If the offense uses it correctly, they can confuse the opposing coach as to what play is coming next. For this reason, most offenses only use illegal motion at the beginning of the game to get the defense off guard.
Most schools rule that if a player with illegal motion is touched by another player, even if that touch is behind the original moving player, he or she will lose further advantage of illegal movement. For example, if a receiver runs an illegal route and is hit by a defensive back, he or she would not be able to use further illegal movement benefits of that play.
However, some coaches believe that if a player with illegal motion is touched by another player, even if that touch is behind the original moving player, he or she should be allowed to continue with the benefit of the illegal movement.
When the ball is snapped, no player may be advancing toward the line of scrimmage. All other players must remain in their spots at all times. If an eligible receiver on the line goes to a different position on the line (other than forward), he must reset before the snap. It is an unlawful motion if he does not reset. For example, if a back moves laterally across the line after the snap, that is a violation.
The exception to this rule is when a team wants to get a free rusher into the game. The coordinator might signal something like "Break right," "Blitz left," or simply "Hot!" When they do this, any player, even one who isn't normally a linebacker or defensive end, can leave their spot and rush the quarterback.
Players can also cross the line during a handoff or on a sweep play if they are flowing to the outside. These are called "wide" crosses because they go beyond just the usual linemen. A back can cross the line too, even if it's illegal for him to do so. This allows the coach to have more flexibility with his offensive scheme and use different combinations of players on each play.
Finally, a player can cross the line even if it's not legal for him to do so. For example, a player might cross the line to help block a defender off from the passer. Or he might cross the line to grab a receiver and pull him downfield.
Receivers in leagues that allow forward motion can start the play racing down the field, perhaps allowing them to go past defenders. Only players in the backfield and not on the line of scrimmage may be in motion at the time of the snap in all forms of football.
In American football, forward motion is when a player who is not in the backfield and is therefore considered to be a receiver starts running toward the end zone or another player who is not in the backfield and is therefore also considered to be a receiver begins running after the ball is snapped. The term is used because it appears as though the players are moving forward even though they may actually be going sideways or backwards.
In Australian rules football, forward movement is when a player has moved at least five metres from their original position before the ball is kicked. This could be either forwards or backwards, depending on where the player was positioned prior to the kick.
In rugby league, forward movement is when a player has moved more than ten yards from their previous position without returning to midfield. A player can also be awarded a penalty if they enter the opposition's half of the field when offside.
In rugby union, players are allowed to move up to seven yards horizontally and vertically without being declared out of bounds.
It's not illegal! There is no regulation requiring you to place the ball between your legs. You can't hold onto the ball and run forward instead of snapping it; you can't imitate a snap and not snap it; and you can't hold onto the ball and run forward instead of snapping it. This rule exists only because old photographs sometimes show players with the ball between their legs. There are two ways to legally snap the ball: a lateral swing, where you swing the arm across your body and snap the ball toward the opposite side of the field; or a forward swing, where you swing the arm straight back and snap the ball forward.
The ball must be held in the hands until the moment of the snap. Once it's in the hands of the holder, they are free to do whatever they want with it. Most often, that means throwing it forward into the end zone. However, if they take too long to release it, another player may be allowed to take over by simply catching it out of their hands.
There are times when it may appear that a player has snapped the ball between their legs, but this is not legal. For example, if a quarterback were to slide and roll away from the play while keeping control of the ball, he would be considered to still have the ball in his hand at the point of contact.