Soccer rules
Rules
There are 17 rules in the official rules of the soccer game. The same rules are designed to apply to all levels of soccer, although certain modifications for groups such as juniors, seniors, women and people with physical disabilities are permitted. The rules are often framed in broad terms, which allow flexibility in their application depending on the nature of the game. The rules of the game are published by FIFA, but are maintained by the International Football Association Board (IBAF), not FIFA itself. In addition to the seventeen rules, numerous IBAF decisions and other directives contribute to the regulation of soccer. The most complex of the rules is offside. The offside law limits the ability of attacking players to receive the ball when closer to the opponent's goal line than: the ball itself; the second-to-last defending player (which can include the goalkeeper); and the half-way line.
Players, equipment, and officials
Each team consists of a maximum of eleven players (excluding substitutes), one of whom must be the goalkeeper. Competition rules may state a minimum number of players required to constitute a team, which is usually seven. Goalkeepers are the only players allowed to play the ball with their hands or arms, provided they do so within the penalty area in front of their own goal. Though there are a variety of positions in which the outfield (non-goalkeeper) players are strategically placed by a coach, these positions are not defined or required by the rules.
The basic equipment are required to wear includes a shirt, shorts, socks, footwear and adequate shin guards. Headgear is not a required piece of basic equipment, but players today may choose to wear it to protect themselves from head injury. Players are forbidden to wear or use anything that is dangerous to themselves or another player, such as jewellery or watches. The goalkeeper must wear clothing that is easily distinguishable from that worn by the other players and the match officials.
A number of players may be replaced by substitutes during the course of the soccer games. The maximum number of substitutions permitted in most competitive international and domestic league games is three, though the permitted number may vary in other competitions or in friendly matches. Common reasons for a substitution include injury, tiredness, ineffectiveness, a tactical switch, or timewasting at the end of a finely poised game. In standard adult matches, a player who has been substituted may not take further part in a match. IBAF recommends that "that a match should not continue if there are fewer than seven players in either team." Any decision regarding points awarded for abandoned games is left to the individual football associations.
A game is officiated by a referee, who has "full authority to enforce the rules of the game in connection with the match to which he has been appointed", and whose decisions are final. The referee is assisted by two assistant referees. In many high-level games there is also a fourth official who assists the referee and may replace another official should the need arise.
Pitch
As the rules were formulated in England, and were initially administered solely by the four British football associations within IFAB, the standard dimensions of a football pitch were originally expressed in imperial units. The rules now express dimensions with approximate metric equivalents (followed by traditional units in brackets), though popular use tends to continue to use traditional units in English-speaking countries with a relatively recent history of metrication, such as Britain.
The length of the pitch for international adult matches is in the range of 100–110 m (110–120 yd) and the width is in the range of 64–75 m (70–80 yd). Fields for non-international matches may be 91–120 m (100–130 yd) length and 45–91 m (50–101 yd) in width, provided that the pitch does not become square. Although in 2008, the IFAB initially approved a fixed size of 105 m long and 68 m wide as a standard pitch dimension for A international matches,[40] this decision was later put on hold and was never actually implemented.
The longer boundary lines are touchlines, while the shorter boundaries (on which the goals are placed) are goal lines. A rectangular goal is positioned at the middle of each goal line. The inner edges of the vertical goal posts must be 7.32 m (8 yd) apart, and the lower edge of the horizontal crossbar supported by the goal posts must be 2.44 m (8 ft) above the ground. Nets are usually placed behind the goal, but are not required by the rules.
In front of each goal is an area known as the penalty area. This area is marked by the goal line, two lines starting on the goal line 16.5 m (18 yd) from the goalposts and extending 16.5 m (18 yd) into the pitch perpendicular to the goal line, and a line joining them. This area has a number of functions, the most prominent being to mark where the goalkeeper may handle the ball and where a penalty foul by a member of the defending team becomes punishable by a penalty kick. Other markings define the position of the ball or players at kick-offs, goal kicks, penalty kicks and corner kicks.
Laws of the Game, read more here...