American football , known in the United States simply as football and sometimes as gridiron outside the United States and Canada, [1] [2] is a sport played between two teams of eleven. The objective of the game is to score points by advancing the ball into the opposing team's end zone. The ball can be advanced by running with it or throwing it to a teammate.
Points can be scored by carrying the ball over the opponent's goal line , catching a pass thrown over that goal line, kicking the ball through the opponent's goal posts or tackling an opposing ball carrier in his own end zone. In the United States, the major forms are high school football , college football and professional football , which are played under slightly different rules. Other minor professional leagues also exist in the U.
The sport is also played in Europe, [4] [5] [6] Japan , Mexico , and other several countries. The International Federation of American Football acts as an international governing body for the sport, but the organization has little standing in the United States. American football is closely related to Canadian football but with some differences in rules and the field. An American football team at the turn of the 20th century. Note the continued use of a rugby-type ball front row, right.
The history of American football can be traced to early versions of rugby football and association football. Many games known as "football" were being played at colleges and universities in the United States in the first half of the 19th century. American football resulted from several major divergences from rugby football , most notably the rule changes instituted by Walter Camp , considered the "Father of American Football".
Among these important changes were the introduction of the line of scrimmage and of down-and-distance rules. In the late 19th and early 20th centuries, game play developments by college coaches such as Eddie Cochems , Amos Alonzo Stagg , Knute Rockne , and Glenn "Pop" Warner helped take advantage of the newly introduced forward pass.
