What is STV (Single Transferable Vote)?
STV uses preferential voting in multi-member constituencies. Each voter gets one vote, which can transfer from their first-preference to their second-preference and so on, as necessary. Candidates don't need a majority of votes to be elected, just a known 'quota', or share of the votes, determined by the size of the electorate and the number of positions to be filled.If your preferred candidate has no chance of being elected or has enough votes already, your vote is transferred to another candidate in accordance with your instructions. STV thus ensures that very few votes are wasted, unlike other systems, especially First-Past-the-Post, where only a small number of votes actually contribute to the result. - Electoral Reform Society source: http://www.electoral-reform.org.uk/article.php?id=48
