American Football

American football, known in the United States simply as football, is a competitive team sport known for its physical roughness despite being a highly strategic game. The object of the game is to score points by advancing the pointed-oval shaped ball into the opposing team's end zone. The ball can be advanced by carrying it (a running play) or by throwing it to a teammate (a passing play). Points can be scored in a variety of ways, including carrying the ball over the goal line, throwing the ball to another player past the goal line or kicking it through the goal posts on the opposing side. The winner is the team with the most points when the time expires and the last play ends.
Outside the United States, the sport is referred to as American football to differentiate it from other football games. In Australia and New Zealand the game is known as Gridiron, although in America the word "gridiron" refers only to the playing field.
While baseball is known as America's "national pastime," football is the most popular American sport and has been since 1972, according to the Gallup Poll. Football's popularity continues to grow; the percentage of Americans who say football is their favorite sport to watch (43%) is higher now than at any other time. Football's American TV viewership ratings far surpass those of other sports. The day of the National Football League championship, the Super Bowl, is one of the biggest occasions for social gatherings in the U.S. and is sometimes referred to as an unofficial national holiday.
Befitting its status as a popular sport, football is played in leagues of different size, age, and quality, in all regions of the country. Organized football is played almost exclusively by men and boys, although a few amateur and semi-professional women's leagues have begun play in recent years.
The 32-team National Football League (NFL) is currently the only major professional American football league. There are no developmental or minor leagues, but the similar sports Arena football and Canadian football are considered lower-level leagues.
RULES
American football is played on a field 120 yards (109.7 m) long by 160 feet (48.8 m) wide. The longer boundary lines are sidelines, while the shorter boundary lines are end lines. Near each end of the field is a goal line; they are 100 yards (91.4 m) apart. A scoring area called an end zone extends 10 yards (9.1 m) beyond each goal line to each end line.
Yard lines cross the field every 5 yards, and are numbered from each goal line to the 50-yard line, or midfield (similar to a typical rugby league field). Two rows of lines, known as inbounds lines or hash marks, parallel the side lines near the middle of the field. All plays start with the ball on or between the hash marks.
At the back of each end zone are two goal posts (also called uprights) that are 18.5 feet (5.6 m) apart (24 feet (7.3 m) in high school). The posts are connected by a crossbar 10 feet (305 cm) from the ground.
Each team has 11 players on the field at a time. However, teams may substitute for any or all of their players, if time allows, during the break between plays. As a result, players have very specialized roles, and almost all of the 46 active players on an NFL team will play in any given game. Thus, teams are divided into three separate units: the offense, the defense and the special teams.
College football is also popular throughout North America. Nearly every college and university has a football team, no matter its size, and plays in its own stadium. The largest, most popular collegiate teams routinely fill stadiums larger than 60,000. Four college football stadiums, The University of Michigan's Michigan Stadium, Penn State's Beaver Stadium, The University of Tennessee's Neyland Stadium and Ohio State's Ohio Stadium, seat more than 100,000 fans and usually sell out. The weekly autumn ritual of college football includes marching bands, cheerleaders, homecoming, parties, and the tailgate party, and forms an important part of the culture in much of smalltown America. Football is generally the major source of revenue to the athletic programs of schools, public and private, in the United States.