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 runoff elections. In each round, the candidate with the fewest first-preference votes (among the remaining candidates) is eliminated. This continues until only one candidate is left. Instant runoff falls under the plurality-with-elimination family of voting methods, and is thus closely related to methods like the two-round runoff system and party primary systems.
Instant-runoff voting has found some use in national elections in several countries, predominantly in the Anglosphere. It is used to elect members of the Australian House of Representatives and the National Parliament of Papua New Guinea, and to elect the head of state in India, Ireland, and Sri Lanka.