The contestant is someone who competes in the battle. They are usually part of a game show or some reality TV show. They usually have to compete against one another passing through rounds until only one of them remains as a winner. They randomly gets selected from the general public through a qualification system like general knowledge or some IQ test and in case of a game show and the reality TV show contestant can be selected on the basis of their talents.
The celebrity version of the reality shows also exists in which we can come across participants who are the celebrity. Sometimes game shows also target celebrity participants. In general reality TV show sets up some task for the contestant which they have to complete it in allocated time limit. That can be anything from singing to dancing or to get confined in a house also performs some other task like balancing on a rope etc., the contestant is the one who knows how to cope with any situation they have to face during the show.