result of this is that the first round of voting tends to eliminate the lesser candidates, and there is always the possibility that nobody wins. Instant-runoff voting Instant-runoff voting (IRV) (also known as preferential voting or ranked-choice voting) like the exhaustive ballot involves multiple reiterative counts in which the candidate with fewest votes is eliminated each time. Whilst the exhaustive ballot and the two-round system both involve voters casting a separate vote in each round, under instant-runoff, voters vote only once. This is possible because, rather than voting for only a single candidate, the voter ranks all of the candidates in order of preference. These preferences are then used to transfer the votes of those whose first preference has been eliminated during the course of the count. Because the two-round system and the exhaustive ballot involve separate rounds of voting, voters can use the results of one round to decide how they will vote in the next, whereas this is not possible under IRV. Because it is necessary only to vote once, IRV is used for elections in many places. For such as Australian general and state elections (called preferential voting). In the United States, it's known as ranked-choice voting and is used in a growing number of states and localities. In Ireland it is known as single transferable vote and is used for presidential elections and parliamentary elections. Variants of instant-runoff voting can be designed to reflect the same rules as a two-round voting system. If no single candidate has an absolute majority of votes then only the two highest polling candidates progress to the second count, while all other candidates are excluded and their votes redistributed according to the recorded preferences for continuing candidates. One variant that works this way is called the Contingent vote, detailed below. Contingent vote The contingent vote is a variant of instant-runoff voting that has been used in the past in Queensland, Australia. Under the contingent vote voters cast only one vote, by ranking all of the candidates in order of preference. However it involves only two rounds of counting and uses the same rule for eliminating candidates as the two-round system. After the first round all but the two candidates with most votes are eliminated. Therefore, one candidate always achieves an absolute majority in the second round. Because of these similarities the contingent vote tends to elect the same winner as the