American football, known in the United States and Canada simply as football, and often as Gridironor Tackle football outside North America, is a competitive team sport known for combining strategy with physical play. American Football has it roots in both soccer and rugby.
In American football, each team has 11 players on the field at a time, and 4 of them are guards, and 7 are linemen. However, teams may substitute for any or all of their players, if time allows, during the break between plays. A standard football game consists of four 15-minute quarters, with a 12 minute half-time intermission after the second quarter. The ball is a similar shape to a Rugby ball, and is generally made from leather. It weighs approximately 400 grams.
