Instant-runoff voting

Instant-runoff voting (IRV) is a voting system used for single-winner elections in which voters have one vote, but can rank candidates in order of preference. In an IRV election, if no candidate receives a majority of first choices, the candidate with the fewest number of votes is eliminated, and ballots cast for that candidate are redistributed to the continuing candidates according to the voters' indicated preference. This process is repeated until one candidate obtains a majority. The term 'instant runoff voting' is used because this process simulates a series of run-off elections. In some implementations a winner may be declared with less than a majority of ballots cast, based on a plurality in the last round, in other implementations, the failure of any candidate to obtain a majority will result in a runoff or other process.
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