Infractions of the rules are punished with penalties, typically a loss of yardage of 5, 10 or 15 yards against the penalized team. Minor violations such as offside (a player from either side encroaching into scrimmage zone before the play starts) are penalized five yards, more serious penalties (such as holding) are penalized 10 yards, and severe violations of the rules (such as face-masking) are typically penalized 15 yards. Depending on the penalty, the penalty yardage may be assessed from the original line of scrimmage, from where the violation occurred (for example, for a pass interference infraction), or from where the ball ended after the play. Penalties on the offence may, or may not, result in a loss of down; penalties on the defence may result in a first down being automatically awarded to the offence. For particularly severe conduct, the game official(s) may eject players (ejected players may be substituted for), or in exceptional cases, declare the game over and award victory to one side or the other. Penalties do not affect the yard line which the offence must reach to gain a first down (unless the penalty results in a first down being awarded); if a penalty against the defence results in the first down yardage being attained, then the offence is awarded a first down.

What is the usual penalty when the rules of play are violated?