Immunity Challenge

The Immunity Challenge is often considered the most important aspect of the game. Winning this type of challenge will secure a tribe or an individual safety for the following tribal council.

Tribal Immunity
During the tribal phase of the game, the tribes vie for the ownership of the Immunity Idol. The winning tribe will be granted safety from the upcoming Tribal Council.

In rare cases, there are double eliminations and both tribes go to Tribal Council, where the Immunity Idol temporarily retires and is replaced with the Immunity Necklace which is usually only available post-merge. But after the double boot twist, the idol returns until the merge.

In, the first post-merge Immunity Challenge involved the castaways being divided into two teams, and as such the Tribal Immunity format was used with the winners of the challenge being abstained from Tribal Council.

Giving Tribal Immunity Away
To date, there have been two instances when a tribe has given up their Tribal Immunity.
 * In, Jeff Probst announced that if Moto (the winning tribe) wanted to keep their luxurious campsite, they must sacrifice Immunity to Ravu, which they did.
 * In, the Manono tribe went to Tribal Council after winning Immunity to vote out Bill Posley, thus granting Salani exemption.

Forfeiting Tribal Immunity

 * In, the Bikal tribe forfeited an Immunity Challenge to go to Tribal Council and vote out Brandon Hantz after he sabotaged their camp.

Individual Immunity
After the merge, where there is only one existing tribe, the remaining contestants compete in individual challenges to seek possession of the Immunity Necklace, which guarantees safety at Tribal Council for its bearer. Unlike the tribal Immunity Idol, which gives exemption to its host, the incumbent wearer of the necklaces still must attend Tribal Council and cast a vote, but that player cannot be voted out. Since, individual immunity is transferable, giving safety to its new wearer, while leaving the original winner vulnerable. The longest individual immunity challenge was the final immunity challenge in . Katie Gallagher, Tom Westman, and Ian Rosenberger held onto buoys for eleven hours and fifty-five minutes (Gallagher dropped out after five hours).

On some occasions, Individual Immunity has been played for during the pre-merge stages of the game, usually occurring during a Double Tribal Council. It can work one of four ways:
 * An Individual Immunity necklace appears at a certain location on the island. The first members of each tribe to get to them are granted Individual Immunity in some form.
 * Members of both tribes compete simultaneously for a shot at wining Individual Immunity
 * One tribe wins a reward, and the members of that winning tribe then compete for Individual Immunity.
 * One tribe wins a reward during a Double Tribal Council. As part of their reward, they are able to give Individual Immunity in some form to a member of the tribe who goes second. (Palau, )

In, , and , as only one castaway won Individual Immunity at a Double Tribal Council, they would grant Individual Immunity to a member of the other tribe.

No Immunity
There has been one case where no one post-merge has come to Tribal Council with immunity. During, the Jury won the Day 37 Immunity Challenge, resulting in no one having immunity. Darrah Johnson was voted out unanimously.