In one case, Fiji, on the day before filming was to start after they had dismissed their alternates, one of the castaways opted out of the competition, forcing production to start with 19 players and adapting the activities of the first few days to accommodate the odd number of players.
Tribes may be predetermined by production before filming starts.
The following description of the show is based primarily on the U. version of Survivor, though the general format applies to all international versions. version host Jeff Probst noted that while 16 castaways assists in splitting the tribes with respect to age and sex, they have used 18 or 20 to provide them "wiggle room" in case of player injury or if one should want to quit the game.
Players for each season are selected through applicants and casting calls, down-selecting to between 16 and 20 players and additional alternates. These players undergo physical and psychological evaluation to make sure they are physically and mentally fit for the survival endurance and will not likely quit during the filming period, replacing those that are questionable with the alternates.
Episodes typically cover the events that occurred over two to three days since the start of the game or previous Tribal Council, including Challenges and events that occur at the tribes' camps.
Each episode typically ends with the Tribal Council and subsequent elimination of the voted-out player.
In other cases, the tribes may be created by the castaways through schoolyard picks.
Most often, only two tribes are featured, but some seasons have begun with three or four tribes.
Tribes are typically given minimal resources, such as a machete, water canteens, cooking pots, and staples of rice and grains, though this will vary from season to season.The contestants compete in challenges for rewards and immunity from elimination.The contestants are progressively eliminated from the game as they are voted out by their fellow contestants until only one remains and is awarded the grand prize and is named the "Sole Survivor." The format for Survivor was created in 1992 by the British television producer Charlie Parsons for a United Kingdom TV production company called Planet 24, but the Swedish version, which debuted in 1997, was the first Survivor series to actually make it to television. Survivor, through its seasons and various international versions, has maintained the basic premise of the game despite several new rules and gameplay twists introduced in later seasons.In the game, the contestants, known as castaways, are split into tribes and assigned separate camps at the filming's location, typically a tropical setting.As a tribe, the castaways must survive the elements, construct shelter, build fire, look for water, and scrounge for food and other necessities for the entire length of the game, which is generally 39 days in the American version, but has ranged from 20 days (as in the French special seasons) to 134 days (as in some seasons of the Turkish edition).In the second half of the game, the tribes are merged into a single tribe, and challenges are played at an individual level for individual rewards and immunity.