Contestants are either applicants who submitted audition tapes or went to casting calls or were basically recruited. Other contestants such as Jaclyn Schultz and Jon Misch initially applied for The Amazing Race, but they were suggested to apply for Survivor: San Juan del Sur. Applicants would be narrowed down to a shortlist.
Once the cast is selected, production has the contestants fill out several visa applications to conceal the actual country they will be filming at. Once at the filming location, the contestants would be sequestered to Ponderosa until filming begins.
Each season of Survivor ranges from having 16 to 20 castaways, each competing to become the Sole Survivor of the season. Each castaway would be assigned on a tribe (either by the production's choice or by Schoolyard Pick by the contestants themselves), although there are times that tribes are not assigned on the first day, and there is an instance in Survivor: Palau where two castaways, Jonathan Libby and Wanda Shirk, were eliminated before tribes were assigned.
The castaways have to compete in a secluded region (e.g. an island or savannah) where they have to stay there for 39 days (except for Survivor: The Australian Outback, where it was 42 days), avoiding elimination. The castaways compete in two kinds of challenges: the Reward Challenge, where the tribe, a single or a group of castaways could win for a reward like tools for the camp, food, or a trip on spots outside the game; and the Immunity Challenge where castaways compete for exemption from Tribal Council, or individual immunity where individual(s) cannot be voted out in Tribal Council.
On Day 39, the final two or three castaways would face the recent castaways eliminated in the game in Final Tribal Council which consists the jury, who would have the power to choose which of the remaining castaways would become the Sole Survivor.
Castaways usually carry in the game clothes and a bag, where they are sometimes allowed to carry a Luxury Item. The castaways are also instructed to wear their buffs all the time to make viewers distinguish easily what tribe each castaway is assigned to.
All-Stars, Guatemala, Micronesia, Heroes vs. Villains, Redemption Island, South Pacific, Philippines, Caramoan, Blood vs. Water, Cambodia, Game Changers, Edge of Extinction, and Winners at War all featured castaways from seasons past. They are known as returning players.
- There are currently 590 castaways who have played Survivor (293 male castaways, 297 female castaways).
- Of all the castaways, 103 have participated in multiple seasons, with 73 castaways competing twice, 23 castaways competing three times, 6 castaways competing four times, and 1 competing five times.
- Of all the castaways, 32 of them have been evacuated due to an emergency or voluntarily ejected themselves from the game. Four players (Jenna Morasca, Susan Hawk, Colton Cumbie, and Sandra Diaz-Twine) quit on their subsequent attempts at the game, while four other players, Jonathan Penner, James Clement, Erik Reichenbach, and Terry Deitz, were evacuated on their subsequent attempts.
- If certain information from the outside world is urgently needed to be relayed a castaway (e.g. death of a family member), the contestant must be pulled out from the game before knowing the said information, as seen in Survivor: Cambodia, when Terry Deitz was rushed home to be with his critically ill son.
- Host Jeff Probst explained that the increase of contestants from 16 to 18-20 is to provide more "wiggle room" (i.e. to have less preempted Immunity Challenges and Tribal Councils) in case of quits or medical evacuations.