Players, equipment and officials
The basic equipment players are required to wear includes a shirt, shorts, socks, footwear and adequate shin guards. Players are forbidden to wear or use anything that is dangerous to themselves or another player (including jewelry 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 game. The maximum number of substitutions permitted in most competitive international and domestic league games is three, though the number permitted may be varied in other leagues or in friendly matches. Common reasons for a substitution include injury, tiredness, ineffectiveness, a tactical switch, or as a defensive ploy to use up a little time at the end of a finely poised game. In standard adult matches, a player who has been substituted may not take further part in the match.
A game is officiated by a referee, who has "full authority to enforce the Laws of the Game in connection with the match to which he has been appointed" (Law 5), and whose decisions are final. The referee is assisted by two assistant referees. In many high-level games there is also a fourth official (and in the world cup a fifth official), who assist(s) the referee and may replace another official should the need arise.
Due to the original formulation of the Laws in England and the early supremacy of the four British football associations within IFAB, the standard dimensions of a football pitch were originally expressed in imperial units. The Laws now express dimensions with approximate metric equivalents (followed by traditional units in brackets), though popular use tends to continue to use traditional units.
The length of the rectangular field (pitch) specified for international adult matches is in the range 100-110m (110-120 yards) and the width is in the range 65-75m (70-80 yards). Fields for non-international matches may be 100-130 yards length and 50-100 yards in width. The longer boundary lines are touchlines or sidelines, while the shorter boundaries (on which the goals are placed) are goal lines. On the goal line at each end of the field a rectangular goal is centered. The inner edges of the vertical goal posts must be 8 yards (7.32m) apart, and the lower edge of the horizontal crossbar supported by the goal posts must be 8 feet (2.44m) above the ground. Nets are usually placed behind the goal, but are not required by the Laws.
In front of each goal is an area of the field known as the penalty area (colloquially "penalty box", "18 yard box" or simply "the box"). This area is marked by the goal-line, two lines starting on the goal-line 18 yards (16.5m) from the goalposts and extending 18 yards 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 penal foul by a defender becomes punishable by a penalty kick.
The field has other field markings and defined areas; these are described in the main article above.
Duration and tie-breaking methods
A standard adult football match consists of two periods of 45 minutes each, known as halves. There is usually a 15-minute "half-time". The end of the match is known as full-time.
The referee is the official timekeeper for the match, and may make an allowance for time lost through substitutions, injured players requiring attention, or other stoppages. This added time is commonly referred to as stoppage time or injury time. The amount of time is at the sole discretion of the referee, and the referee alone signals when the match has been completed. In matches where a fourth official is appointed, toward the end of the half the referee will signal how many minutes remain to be played, and the fourth official then signals this to players and spectators by holding up a board showing this number.
In league competitions games may end in a draw, but in some knockout competitions if a game is tied at the end of regulation time it may go into extra time, which consists of two further 15-minute periods. If the score is still tied after extra time, some competitions allow the use of penalty shootouts (known officially in the Laws of the Game as "kicks from the penalty mark") to determine which team will progress to the next stage of the tournament. Goals scored during extra time periods count toward the final score of the game, but kicks from the penalty mark are only used to decide the team that progresses to the next part of the tournament (with goals scored in a penalty shootout not making up part of the final score).
Competitions held over two legs (in which each team plays at home once) may use the away goals rule to attempt to determine which team progresses in the event of an equal aggregate score line. If the result is still equal following this calculation kicks from the penalty mark are usually required, though some competitions may require a tied game to be replayed.
In the late 1990s, the IFAB experimented with ways of making matches more likely to end without requiring a penalty shootout, which was often seen as an undesirable way to end a match. These involved rules ending a game in extra time early, either when the first goal in extra time was scored (golden goal), or if one team held a lead at the end of the first period of extra time (silver goal). Golden goal was used at the World Cup in 1998 (France) and 2002 (Japan-South Korea). The first World Cup game decided by a golden goal was France's victory over Paraguay in 1998. In Euro 1996, Germany was the first nation to score a golden goal in a major competition, beating Czech Republic in the final. Silver goal was used in Euro 2004 (Portugal). Both these experiments have been discontinued by IFAB.
Ball in and out of play
Under the Laws, the two basic states of play during a game are ball in play and ball out of play. From the beginning of each playing period with a kick-off (a set kick from the centre-spot by one team) until the end of the playing period, the ball is in play at all times, except when either the ball leaves the field of play, or play is stopped by the referee. When the ball becomes out of play, play is restarted by one of eight restart methods, the method used depending on the reason for the ball going out of play:
Fouls and misconduct
A foul occurs when a player commits a specific offence listed in the Laws of the Game when the ball is in play. The offences that constitute a foul are listed in Law 12. Handling the ball, tripping an opponent, or pushing an opponent, are examples of "penal fouls", punishable by a direct free kick or penalty kick depending on where the offence occurred. Other fouls are punishable by an indirect free kick.
The referee may punish a player or substitute's misconduct by a caution (yellow card) or sending-off (red card). Misconduct may occur at any time, and while the offences that constitute misconduct are listed, the definitions are broad. In particular, the offence of "unsporting behavior" may be used to deal with most events that violate the spirit of the game, even if they are not listed as specific offences.
Rather than stopping play, the referee may allow play to continue when its continuation will benefit the team against which an offence has been committed. This is known as "playing an advantage". The referee may "call back" play and penalize the original offence if the anticipated advantage does not ensue within a short period of time, typically taken to be four to five seconds. Even if an offence is not penalized because the referee plays an advantage, the offender may still be sanctioned for any associated misconduct at the next stoppage of play.
The offside law effectively limits the ability of attacking players to remain forward (i.e. closer to the opponent's goal-line) of both the ball and the second-last defending player