In cricket, substitutes can be used to fill in for injured players. The umpires must approve the substitution. Anybody can substitute, even members of the crowd or coaching staff. One example is the 1988 India tour where a New Zealand journalist took over the field for the New Zealand player.
Test cricket allows the use of concussion substitutions
The ICC recently introduced a rule that allows players to be substituted for concussion. This rule was created in response to growing concerns about head injuries in cricket and other sports. Before the rule, players were not allowed to take time off for injury. Although the rule was not initially implemented in domestic cricket, the New Zealand Cricket Board (Cricket Australia) have made it legal for players who wish to use concussion replacements.
A player cannot be replaced if they sustain a concussion in a Test match. Players may request such replacements from the International Cricket Council, starting with the 2019 season. A player's doctor will decide if the concussion substitute would be a suitable replacement. Also, the replacement must be identical to the original.
They cannot bat
In cricket, a substitute bowler cannot bat. A substitute fielder is able to play in the role of a replacement bowler. However, substitute bowlers cannot bat or bowl. Instead, substitute bowlers must wait for their turn before they are allowed to take an over. A substitute fielder can't play the role as captain or wicket-keeper. Only the umpires can authorize a substitute fielder to be used. In cricket, a substitute fielder is called the "twelfth person". The only exception to this rule is if the player is injured.
Substitutions in cricket are treated differently to other sports. A substitute can replace a player injured or ill during a cricket match. The injured player can't have a substitute bat or bowl while they are being treated. A substitute may only play if the injured player is still recovering from an injury.
They can't bowl
As long as the umpires approve, substitutions can be made for anyone. This could be a crowd member, a reporter on-site, or a member if the coaching staff. One famous example is when a New Zealand journalist took to the field during the team’s tour of India.
A substitute can be used to replace an injured player but he cannot serve as a batsman or captain. A substitute can't take the place of a player with a concussion. Concussion can cause a player to be unable to field or bowl.
They can't be wicketkeepers.
Rules of cricket permit substitutes to be used only when they are necessary. A substitute can not be a captain or wicketkeeper without being nominated by the team. In order to be called into action, they must also have the approval of the umpires. In some games, substitutes cannot be used as captains or wicketkeepers.
While a substitute fielder can take a catch, he cannot serve as a wicketkeeper. In 1884, Billy Murdoch caught Tup Scott when playing as a substitute for England. Others have caught fish while performing substitute roles such as Gursharan Sing and Jackson Bird. These catches are not included in an individual's statistics.
They must be a like-for-like replacement
Cricket replacement rules stipulate that a replacement for a bowler must take place with a replacement who is similar to the one who was injured. This means that an injured specialist batsman must be replaced by a similarly-suited spinner if he is hurt. However, this rule doesn't apply to all players.
The International Cricket Council has established strict rules for substitutions. The rules are designed to prevent the use of substitutions that could be considered tactical. Substitute fielders may only ever be used to fulfill legitimate reasons.