Football is a one of the most popular game of the world.American football was started in 1879 with rules instituted by Walter Camp, player and coach at Yale University.It is a team sport. A game played with a ball on a rectangular field, 100 yards in length, with goal lines and goal posts at either end. Opposing teams of 11 players each attempt to gain possession of the ball and advance it by means of running and passing plays across the opponent's goal line. A team doing so scores a touchdown, worth six points, and then has the opportunity to kick the ball over the goalpost crossbar for one extra point. The goalkeeper is the only player allowed to use his hands or arms to prople the ball into opposing goal. All the other team member are only allowed to use their feet to kick the ball.The team that scores the most goals by the end of the match wins.

The referee is responsible for the entire game, including keeping a record of the game and acting as the timekeeper. The referee makes decisions on penalties, cautions and ejects players for misconduct. Two linesmen are primarily responsible for indicating to the referee when the ball is out of play and which team is entitled to a throw-in, goal kick or corner kick.A coin toss at the beginning of the game determines which team decides between taking the kickoff or defending a chosen side first. The team that does not take the kickoff at the beginning of the game takes the second half kickoff. A team that is scored upon is awarded a kickoff to restart the game.Direct and indirect kicks are the two types of free kicks awarded during a game. A goal can be scored directly from a direct kick. For indirect kicks, the ball must be touched by a player other than the kicker before a goal can be scored. There are nine major offenses, or fouls some of them are explained here. Kicking or attempting to kick an opponent. Tripping an opponent i.e. throwing or attempting to throw an opponent with the legs or by undercutting an opponent with the body. Jumping at an opponent in a way that endangers the player. Charging an opponent in a violent or dangerous manner. If any of the nine major fouls are committed by the defending team in its own penalty area, a penalty kick is awarded to the opposing team.

The major international competition in football is the World Cup, organised by FIFA. This competition takes place over a four-year period. More than 190 national teams compete in qualifying tournaments within the scope of continental confederations for a place in the finals.