Running into the kicker

In American football and Canadian football, a penalty is a sanction called against a team for a violation of the rules, called a foul.Officials initially signal penalties by tossing a bright yellow (American Football) or orange (Canadian football) colored "penalty flag" onto the field toward or at the spot of a foul. Many penalties result in moving the football toward the offending team's end zone, usually either 5, 10, or 15 yards, depending on the penalty. Most penalties against the defensive team also result in giving the offense an automatic first down, while a few penalties against the offensive team cause them to automatically lose a down. In some cases, depending on the spot of the foul, the ball is moved half the distance to the goal line rather than the usual number of yards, or the defense scores an automatic safety.

Because football is a high-contact sport requiring a balance between offense and defense, many rules exist that regulate equality, safety, contact, and actions of players on each team. It is very difficult to always avoid violating these rules without giving up too much of an advantage. Thus, an elaborate system of fouls and penalties has been developed to "let the punishment fit the crime" and maintain a balance between following the rules and keeping a good flow of the game. Players and coaches are constantly looking for ways to find an advantage that stretches the limitations imposed by the rules. For example, in 2016 the Baltimore Ravens had all of their offensive linemen commit holding penalties in order to allow the punter to keep possession of the ball so time would expire for a win, since the game can end on offensive penalties. However, the NFL changed the rules after this to prevent teams from manipulating the game clock. The frequency and severity of fouls can make a large difference in the outcome of a game as well, so coaches are constantly looking for ways to minimize the number and severity of infractions committed by their players.

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