Football is the name of several similar team sports, all of which involve (to varying degrees) kicking a ball with the foot in an attempt to score a goal. The most popular of these sports worldwide is association football, more commonly known as just "football" or "soccer". However the word football is applied to whichever form of football became most popular in each particular part of the world. Hence the English language word "football" is applied to "gridiron football" (a name associated with the North American sports, especially American football and Canadian football), Australian football, Gaelic football, rugby league, rugby union, and related games.
These games involve:
Two teams of usually between 11 and 18 players; some variations that have fewer players (five or more per team) are also popular
a clearly defined area in which to play the game;
scoring goals or points, by moving the ball to an opposing team's end of the field and either into a goal area, or over a line;
goals or points resulting from players putting the ball between two goalposts
the goal or line being defended by the opposing team;
players being required to move the ball—depending on the code—by kicking, carrying or hand passing the ball; and
players using only their body to move the ball.
In most codes, there are rules restricting the movement of players offside, and players scoring a goal must put the ball either under or over a crossbar between the goalposts. Other features common to several football codes include: points being mostly scored by players carrying the ball across the goal line; and players receiving a free kick after they take a mark or make a fair catch.
Peoples from around the world have played games which involved kicking or carrying a ball, since ancient times. However, most of the modern codes of football have their origins in England.
Article Source: http://www.en.wikipedia.org/wiki/Football