During the tribal portion of the game, the tribes compete against each other in challenges that typically require each member to work together in some way. The winning tribe is awarded the Immunity Idol, and is exempt from attending the following Tribal Council, meaning no one from the tribe can be voted out.
Occasionally, Immunity Challenges may be combined with Reward Challenges, with the winning tribe receiving both immunity and reward. In seasons with three tribes competing, typically the highest-placing tribe receives both immunity and reward, while the second highest-placing tribe only receives immunity.
After the tribes have merged, immunity becomes available to the castaways in the form of the Immunity Necklace, which they will compete for in challenges as individuals.
On rare occasions, individual immunity may be rewarded to multiple contestants at a time. When this happens, contestants are usually either placed into teams and compete together, or they compete individually with immunity being given to the top finishers.
In some seasons, individual immunity can be won during the pre-merge portion of the game. This usually happens in seasons that feature a Double Tribal Council, which has the castaways competing for individual immunity to have for when their tribe goes to Tribal Council. There are many ways this has been done:
On Day 24 of Survivor Fan Characters 8: The Midway Island, the first Immunity Challenge of the season ended in a three-way tie between Geena Takahashi, Kiara Gate, and Malik Rishied, who had all dropped out at the same time, after Xero the Lop-Sider pointed out that nobody who had won the first Immunity Challenge in previous seasons had gone on to win the game. After going through the footage, it was eventually decided that Geena had won the challenge, but she forfeited immunity, as did Kiara and Malik, who claimed they were unable to be declared the winners because Geena had beaten them. Irritated, Jeff Probst issued an ultimatum that nobody would receive immunity, and that everyone was vulnerable going into Tribal Council that night.
Schlipa was the first tribe to win a tribal Immunity Challenge.
Wendy was the first contestant to win an individual Immunity Challenge.
Violet and Dustin both hold the record for most individual immunity wins in a single season, with five each.
Violet is tied with Ker for having the most consecutive individual immunity wins in a single season, with four each.
Mariano has won the most tribal Immunity Challenges, with nine. (This is excluding an instance where immunity was surrendered to Mariano by Hantz, as opposed to being won in the challenge.)