Instant-runoff voting

Instant-runoff voting (IRV; US: ranked-choice voting (RCV), AU: preferential voting, UK/NZ: alternative vote) is a single-winner ranked voting election system where one or more eliminations are used to simulate multiple rounds of voting as done in a runoff election. The purpose is to have the winner win with the support of a proven majority of votes cast (or majority of votes still in play at the time of winning). If no candidate takes a majority of votes in the first round, in each subsequent round the candidate with the fewest first-preference votes among the remaining candidates is eliminated and their votes are transferred if possible. This continues until a candidate achieves a majority of votes.