A substitute in the sport of cricket is a replacement player that the umpires allow when a player has been injured or become ill after the nomination of the players at the start of the game. The rules for substitutes all appear in Law 2 of the Laws of cricket.
A substitute can act for the injured or ill player in the field, although he may not bowl, bat, or act as wicket-keeper or as captain, unless otherwise agreed by the captains. A famous example is the 1986 Test between England and New Zealand at Lords, where England used 4 different wicketkeepers due to injury to their original wicketkeeper. (But see "Tactical substitute" below.). A player may bat, bowl and field even if he has had a substitute for part of the game.
A substitute is permitted to take catches as with any other player, and on some occasions does. The first occasion in Test cricket was in the Test between England and Australia in 1884, when Australia's captain, Billy Murdoch, took a catch from his teammate Tup Scott while playing as a substitute for England. The highest number of catches by a substitute fielder in a Test match is four, a record shared by Gursharan Singh, Younis Khan, Virender Sehwag, and Jackson Bird.
In recent years, there have been arguments made for cricket to allow substitutes in First Class games, as cricket remains unique amongst team sports in not permitting full substitutes for either injuries or tactical reasons. Arguments in favour have been made from a perspective of improving the game, coping with increasing injury rates due to the modern schedule, to follow the lead of other sports in trying to manage concussion more responsibly and to provide greater opportunities for players to gain experience in First Class cricket. However, there is an equally strong viewpoint that the nature of the First Class contest may be diminished with a summary suggesting that although medical experts would recommend introduction of substitutes the majority of players are still not in favour.