American football is the latest species in the evolutionary tree of soccer. Its ancestor is rugby, which itself is a descendant of soccer. Football is a true team sport -- no one player can dominate and the team must work together to win. It is also by far the most complex popular sport in the world, with a 220-page rulebook and eight referees on the field at all times.
Football's unique characteristics, both in its own right and as part of the soccer family tree, include:
- Uncontested possession of the right to score. This means that at any one time, there is one team trying to score (the offense) and a team trying to prevent a score (defense). Compare soccer, where teams frequently alternate control of the ball and either team can score at any time.
- The concept of "downs" (where the offense is required to move the ball a certain distance (10 yards) in 4 plays to retain offensive control). If the offense cannot move the ball 10 yards in 4 downs, the defense takes possession of the ball and becomes the offense.
Adjacent to this is the idea of discontinuous play. Football happens in spurts of a play at a time, each play lasting around 10 seconds on average. Soccer, rugby, basketball and most other team sports flow and stoppages of play are rare.
- The forward pass. In soccer, mere contact with the ball with the hands, or indeed the arms, is a foul. In rugby, passes are sidearm or underhand shoves which must always be to a player behind the ball carrier; overhand throws are verboten. Football survives this action in the lateral; a lateral, like a fumble, is a free ball and the first team to obtain the ball gains possession. However, a forward pass (with other restrictions not mentioned here) is thrown to a player in front of the passer and, if not caught, is considered a spent down and the offense retains possession of the ball. (Of course, the defense may catch a forward pass, known as "intercepting", and gain possession.)
The football branch of the tree sprouted on November 6, 1869, between Princeton and Rutgers. Exactly what the hell they played is unclear, so much so that soccer historians believe it to be the first intercollegiate soccer game. At the time it was called the "Boston Game" after its birthplace at Harvard Yard. Basically, a group of kids at Harvard had a game of rugby described to them by an English student and tried to play it on their own without full knowledge of the rules. Whatever they played, it was the impetus for the development of both soccer and football in the U.S.
Much more information can be found on www.nfl.com and at http://library.thinkquest.org/12590/history.htm.