Tiebreaker

A  is a situation where two (or more) individuals share the same amount of votes at Tribal Council with no other person recieving a higher amount. In this event, several instances occur.

About
A tie-breaker situation occurs when two (or more) voting blocs vote for one person from the rival alliance. This forces the contestants to re-vote (those with the tied votes are excluded) with the option to vote for the other person.

Rules
While the first tie vote to ever occur in Survivor: Borneo, was resolved after a revote, its deadlocked tiebreaker remains unknown. However, one thing is certain: If a tie happens, the players in question would not vote, while the remaining players vote again. If the second vote still ends up tied, it would be deadlocked, which is the tricky and controversial aspect of the game.

Earlier Seasons
In Survivor: The Australian Outback and Survivor: Africa, the people involved in the tie vote would make a last-minute plea before the other players vote once again.
 * 1) If a tie occurs, all other tribe members receive immunity and there is a re-vote. The two people that tied in votes cannot vote.
 * 2) If the second vote is deadlocked, votes from previous Tribal Councils will be counted. Whoever had more votes goes home. If the Tribal Council was the tribe's first, or neither of the tied players had past votes, they would be subjected into a tiebreaker challenge. The loser goes home.

The Purple Rock
The infamous Purple Rock tiebreaker was first used in Survivor: Marquesas, in Day 36, where Neleh Dennis and Kathy Vavrick-O'brien were tied 2-2. They pulled out rocks, and in a surprise turn of events, Paschal English, the only contestant who did not receive a vote was eliminated by drawing the purple rock.

Current Rules
If a deadlock tie happens before the Tribal Council with only four contestants remaining, all non-immune contestants would draw rocks. if a tie happens at the Final Four, the tied contestants will be subjected in a fire-starting challenge. The winner stays, the loser is out.

The reason why the Purple Rock is still in use is because this would prevent contestants in forcing a tie vote.