Football is the most popular sport in the United States, surmounting the other sports of the big-three American sports (baseball, basketball, and hockey). The popularity of football fluctuates routinely between the emergence of new stars to replace the old and the controversy that surrounds players during their off-field activities, yet the ratings remain high.
American football holds its roots in rugby and association football (or soccer) in mid-19th century Britain. American football diverged from soccer and rugby after several rule changes instituted by Walter Camp, who is often referred to as 'the Father of American Football'.
These rules were instituted and led to the creation of college football, where college-sponsored football teams play against each other. Rivalries between colleges began to form and bowl games became a college football tradition at the end of the season. The popularity of college football eventually led to the creation of a professional league called the American Professional Football Association, which became the National Football League (NFL) two years later.
The game of football is played between two teams using a football, an egg-shaped ball covered in cowhide with laces, on a football field. The standard football field is 120 yards in length and 53 yards wide and is made of grass. Each end of the football field has a ten-yard endzone with a goal post. The field 100 yards long from endzone to endzone.
There are three parts to a standard football team: the offense, the defense, and the special teams. Each squad of the football team consists of 11 players. The offense attempts to move the ball by running and throwing the football and score points by scoring a touchdown (crossing into the opponent's endzone) or by scoring a field goal (kicking the ball through the yellow upright goal posts).
The defense attempts to stop the offense from scoring points by preventing passes from being completed and tackling the player with the ball to the ground. The special teams unit are players involved with kicking the football, including field goals, punts, and kickoffs.
The game is played over 60 minutes, divided into four quarters, each 15 minutes long. After the second quarter, there is halftime, when the game is halfway over. The game is played on a down cycle, in which the offense has four downs to get the ball past the first down line. The first down line is 10 yards downfield from where the ball is initially spotted to start the down cycle. If the offense does not reach the first down line after the fourth down, the ball is given to the opposing team.
There are quite a few ways to score in football, including a touchdown (worth six points), the extra point (worth one point and performed following a touchdown), the safety (worth two points for tackling the ball carrier in their own endzone), and the two-point conversion (worth two points and performed following a touchdown).
The game is umpired by referees on the field who are responsible for watching the action and calling appropriate penalties, or illegal actions when they occur. There are also reviews for certain plays that are reviewed by the referees, as well as by the NFL rule makers.
The NFL and football are more popular than ever. Expansions into other countries, including Mexico and England, continue and it may not be long until we see the first NFL team in a country other than America.