Association football, more commonly known as football or soccer, is a sport played between two teams of eleven players with a spherical ball. At the turn of the 21st century, the game was played by over 250 million players in over 200 countries, making it the world's most popular sport.[1][2][3][4] The game is played on a rectangular field of grass or green artificial turf, with a goal in the middle of each of the short ends. The object of the game is to score by driving the ball into the opposing goal.