<human>:  I want to learn some facts about American football.
<bot>: American football is a sport played between two teams of 11 players each. The objective of the game is to move a ball down the field and score points by crossing the opposing team's goal line or kicking the ball through their uprights. Points can also be scored by tackling the opposing team's players in their end zone or their own end zone. The team with the most points at the end of the game is declared the winner. Some of the most common rules of American football include tackling, holding, and clipping. American football is mainly played in the United States, but it is slowly gaining popularity in other parts of the world.