Substitute (soccer)

A substitute is a player in football who is brought on to the pitch during a match in exchange for an existing player. Substitutions are generally made to replace a player who has become tired, injured or who is not performing well, or for other tactical reasons such as bringing an attacker on in place of a defender when goals are required.

FIFA Rules

According to FIFA's Laws of Association Football (2005) http://www.fifa.com/en/regulations/regulation/0,1584,3,00.html:

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Official Competitions

• Up to a maximum of three substitutes may be used in any match played in an official competition organised under the auspices of FIFA, the confederations or the member associations.
• The rules of the competition must state how many substitutes may be nominated, from three up to a maximum of seven.

Other Matches

• In national A team matches, up to a maximum of six substitutes may be used.
• In all other matches, a greater number of substitutes may be used provided that:
• the teams concerned reach agreement on a maximum number;
• the referee is informed before the match.
• If the referee is not informed, or if no agreement is reached before the match, no more than six substitutes are allowed.