Shut out

In team sports, a shutout (a clean sheet (UK English) in association football) is a game in which one team prevents the other from scoring any points. While possible in most major sports, they are highly improbable in some sports, such as basketball.

Shutouts are usually seen as a result of effective defensive play even though a weak opposing offense may be as much to blame. Some sports credit individual players, particularly goalkeepers and starting pitchers, with shutouts and keep track of them as statistics; others do not.

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. In the decade of the 2000s there were 89 shutouts in 2,544 NFL regular-season games, for an average of slightly more than one shutout every two weeks in an NFL season.

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.

In association football a team, defence or goalkeeper may be said to "keep a clean sheet" if they prevent their opponents from scoring any goals during an entire match. Because association football is a relatively low-scoring game, it is common for one team, or even both teams, to score no goals. A theory as to the term's origin is that sports reporters used separate pieces of paper to record the different statistical details of a game. If one team did not allow a goal, then that team's "details of goals conceded" page would appear blank, leaving a clean sheet.

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