American football, known in the United States simply as football and often as gridiron or tackle football outside the United States, is a competitive team sport known for combining strategy with physical play. 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 carrying it (a running play) or by throwing it to a teammate (a passing play). Points can be scored in a variety of ways, including carrying the ball over the opponent's goal line, catching a pass thrown over that goal line, kicking the ball through the goal posts at the opponent's end zone, or tackling an opposing ball carrier within his end zone. The winner is the team with the most points when the time expires.