Jelaskan American football dari Nirbobol

A shutout in American football is uncommon but not exceptionally rare. Keeping an opponent scoreless in American football requires a team's defense to be able to consistently shut down both pass and run offenses over the course of a game. The difficulty of completing a shutout is compounded by the many ways a team can score in the game. For example, teams can attempt field goals, which have a high rate of success. The range of NFL caliber kickers makes it possible for a team with a weak offense to get close enough (within 50 yards) to the goalposts and kick a field goal. Of 2,544 regular season NFL games from 2000–2009, 89 (3.5%) were shutouts.

There are at least five instances in American football in which a team had been shut out throughout an entire season, and four in which a team has shut out all of their opponents in the season (the longest of these being the ten-game perfect season in which the 1933 Providence Huskies did not concede a single point).

The achievement of a shutout is much more difficult in Canadian football, where scoring and offensive movement is generally more frequent and a single point can be scored simply by punting the ball from any point on the field into the end zone.