The ball in and out of play is the ninth law of the Laws of the Game of association football, and describes to the two basic states of play in the game.

In play

The ball remains in play from the beginning of each playing period to the end of that period, except when:

• The ball leaves the field by entirely crossing a goal line or touch line (this includes when a goal is scored); or
• Play is stopped by the referee (for example when a foul has been committed, a player is seriously injured, or the ball becomes defective).

Note that when the ball is in play it remains in play if it rebounds from a goalpost, crossbar, corner flag, referee or assistant referee, assuming that they are on the field of play at the time.

When the ball is in play players may play the ball, contest the ball, and goals may be scored. Players are liable to punishment for committing either fouls

Foul (football)

A foul in association football is an unfair act by a player which is deemed by the referee to contravene Law 12 of the Laws of the Game.For an act to be a foul it must:...

 or misconduct

Misconduct (football)

Misconduct in association football is any conduct by a player that is deemed by the referee to warrant a disciplinary sanction in accordance with Law 12 of the Laws of the Game. Misconduct may occur at any time, including when the ball is out of play, during half-time and before and after the...

. Substitutions may not occur whilst the ball is in play.

Out of play

When the ball has left the field of play or play has been stopped by the referee, it becomes out of play until play is recommenced by the appropriate restart.

When the ball is out of play the ball is "dead"; players must not play the ball or interfere with their opponents, and goals cannot be scored. By definition, fouls

Foul (football)

A foul in association football is an unfair act by a player which is deemed by the referee to contravene Law 12 of the Laws of the Game.For an act to be a foul it must:...

 do not occur when the ball is out of play, however misconduct

Misconduct (football)

Misconduct in association football is any conduct by a player that is deemed by the referee to warrant a disciplinary sanction in accordance with Law 12 of the Laws of the Game. Misconduct may occur at any time, including when the ball is out of play, during half-time and before and after the...

 may occur. Substitutions may only be made when the ball is out of play (and then only with the permission of the referee).

Restarts

When the ball becomes out of play, the ball is put back into play be the appropriate restart. The restarts in football are:

• Kick-off: following a goal by the opposing team, or to begin each period of play. (Law 8).
• Throw-in
  Throw-in
  A throw-in is a method of restarting play in a game of Association football.-Procedure:The throw-in is taken from the point where the ball crossed the touch-line. The throw-in is taken by the opponents of the player who last touched the ball when it crossed the touch-line, either on the ground or...
  
  : when the ball has entirely crossed the touch line; awarded to opposing team to that which last touched the ball. (Law 15).
• Goal kick
  Goal kick
  A goal kick, called a goalie kick in some regions,is a method of restarting play in a game of association football.-Award:A goal kick is awarded to the defending team when the ball goes out of the field of play by crossing the goal line when the last person to touch the ball was from the attacking...
  
  : when the ball has entirely crossed the goal line without a goal having been scored and having last been touched by an attacker; awarded to defending team. (Law 16).
• Corner kick
  Corner kick
  A corner kick is a method of restarting play in a game of association football. It was first devised in Sheffield under the Sheffield Rules 1867...
  
  : when the ball has entirely crossed the goal line without a goal having been scored and having last been touched by a defender; awarded to attacking team. (Law 17).
• Indirect free kick
  Indirect free kick
  An indirect free kick is a method of restarting play in a game of association football. Unlike a direct free kick, a goal may not be scored directly from the kick. The law was derived from the Sheffield Rules that stated that no goal could be scored from a free kick...
  
  : awarded to the opposing team following "non-penal" fouls (like obstruction, offside, etc.), certain technical infringements, or when play is stopped to caution/send-off an opponent without a specific foul having occurred. (Law 13).
• Direct free kick
  Direct free kick
  A direct free kick is a method of restarting play in a game of association football following a foul. Unlike an indirect free kick, a goal may be scored directly against the opposing side without the ball having first touched another player.-Award:...
  
  : awarded to fouled team following certain listed "penal" fouls. (Law 13).
• Penalty kick: awarded to fouled team following "penal" foul having occurred in their opponent's penalty area. (Law 14).
• Dropped-ball
  Dropped-ball
  A dropped-ball is a method of restarting play in a game of association football. It is designed to offer no advantage to either side, generally being awarded when play has been stopped due to reasons other than normal gameplay or misconduct.-Award:A drop-ball is not awarded to either team; rather...
  
  : occurs when the referee has stopped play for any other reason (e.g. a serious injury to a player, interference by an external party, or a ball becoming defective). This restart is uncommon in adult games. (Law 8).

Once the ball is out of play, the only restart is the restart appropriate for the reason the ball went out of play in the first place; subsequent actions do not change the restart. For example, if the ball goes out of play because of a foul by Team A against Team B, the restart must be a free kick to Team B even if a Team B player strikes an opponent; offending Team B player would, however, be liable for misconduct (i.e. yellow card

Misconduct (football)

Misconduct in association football is any conduct by a player that is deemed by the referee to warrant a disciplinary sanction in accordance with Law 12 of the Laws of the Game. Misconduct may occur at any time, including when the ball is out of play, during half-time and before and after the...

 or red card

Misconduct (football)

Misconduct in association football is any conduct by a player that is deemed by the referee to warrant a disciplinary sanction in accordance with Law 12 of the Laws of the Game. Misconduct may occur at any time, including when the ball is out of play, during half-time and before and after the...

).

Note, however, that the referee may change the original restart if he realises he has made an error or on the advice of his assistant referees, provided play has not yet restarted. For example, if the ball has gone out of play because the ball was kicked into goal by Team A and the referee has signalled that a goal has been scored, but then notices that an assistant referee has indicated a foul by a Team A player immediately before the goal was scored, the referee would change to the correct restart of a free kick to Team B where the foul occurred.