Professional football (gridiron)

In the United States and Canada, the term professional football includes the professional forms of American and Canadian gridiron football. In common usage, it refers to former and existing major football leagues in either country. Currently (2016), there are multiple professional football leagues in North America: the three best known are the National Football League (NFL) and the Arena Football League (AFL) in the U.S. and the Canadian Football League (CFL) in Canada. The NFL has existed continuously since being so named in 1922.

Compared to the other major professional sports leagues of the United States and Canada, football has comparatively few levels of play and does not have a well-developed minor league system or pyramid, either official or otherwise.

In North America, the top level of professional football is the National Football League, with the Canadian Football League second to the NFL in prominence and pay grade. Despite the lower level of pay, the CFL has greater popularity in Canada because of its long history in the country, the NFL's limited presence in Canada, and a general environment of Canadian cultural protectionism.

Indoor football has also developed in the United States, beginning with the Arena Football League, which formed in 1987. The AFL is the second longest running professional football league in the United States after the NFL, although its current incarnation is a separate entity from the original, which folded due to bankruptcy in 2008. From its debut until 1997, the Arena Football League operated with a monopoly on the indoor game, due to a broad interpretation that virtually all of the league's rules, collectively known as arena football, were covered under its patent; the Professional Indoor Football League successfully defeated the AFL's legal action against it in 1997, opening the possibility for other indoor football leagues to form. Only one significant aspect of the patent, the large rebound nets the AFL has used since its debut to keep balls in play, was fully protected; the patent expired in 2007, although no other professional indoor league has adopted rebound nets since. As of 2011, two national leagues (the AFL and the Indoor Football League), along with several regional professional and semi-pro leagues, are in operation. As of 2011, no professional indoor football league has had any significant presence in Canada (despite an abundance of hockey arenas that are ideal for the game); only one indoor team, the AFL's short-lived Toronto Phantoms (2000 to 2002), has ever played its games in Canada. The all-female Lingerie Football League had operations in Canada from 2011 to 2014, but that league dropped to amateur level by the time the LFL entered the country.

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