Soccer Law 10: The Method of Scoring

Goals

Goals are placed at the center of each goal-line. These consist of two upright posts placed equidistant from the corner flagposts, joined at the top by a horizontal crossbar. The inner edges of the posts must be 7.32 metres (8 yds) apart, and the lower edge of the crossbar must be 2.44 metres (8 feet) above the ground. Nets are usually placed behind the goal, though are not required by the Laws.

Goalposts and crossbars must be white, and made of either wood or metal. Rules regarding the shape of goalposts and crossbars are somewhat more lenient, but they must conform to a shape that does not pose a threat to players.

A point (goal) is scored when the ball completely crosses the goal line between the goal-posts, even if a defending player last touched the ball before it crossed the goal line (see own goal). A goal may, however, be ruled illegal if the player who scored or a member of his team commits an offence under any of the Laws between the time the ball was previously out of play and the goal being scored.

Source: Wikipedia