The single transferable vote (STV) is a proportional representation system and ranked voting rule that elects multiple winners. Under STV, an elector's vote is initially allocated to their first-ranked candidate. Candidates are elected (winners) if their vote tally exceeds the electoral quota. Any surplus votes (those exceeding quota) are transferred from winners to the remaining candidates (hopefuls) according to the surplus ballots' next usable back-up preference.
The system attempts to ensure factions are represented proportionally, without the need for official party lists, by having each winner elected with roughly the same number of votes. There are several variants of the Single Transferable Vote, each with different properties.