DMOZ Sports Football
This category is for topics relating to American rules football, by various measures the most popular spectator team sport in the United States.
The American game is played by two opposing teams of eleven on a 100x53 yard field, delinated by a goal line and an elevated set of goal posts at either end. The offense must move the ball, by passing or running, ten yards in four plays ("downs") towards the opponent's goal line in an attempt to score. If the line is crossed, they score "touchdown," worth six points; otherwise, possession is yielded; scoring and possession may be accomplished through various additional means depending on the rules of the game in question.
Kicking games were practiced in pre-colonial and colonial times under various rules. The first intercollegiate matchup took place on November 6, 1869 between Princeton and Rutgers Universities, but the distinctive rules of American football developed from the merging of the soccer-like rules adopted by Princeton, Rutgers, Yale and Columbia with those of the rugby-like running game observed by Harvard and McGill in the 1870s and 1880s.
Quarterback Passer Rating Calculator
Rates quarterbacks by attempts, completions, passing yards, touchdowns, and interceptions. NFL, NCAA, and Arena Football League calculations available.
Wikipedia: American Football
Hyperlinked encyclopedia article covering the history of the sport and its rules, players, basic strategy, physicality and organization.