The Alternative Vote is a type of voting system. In the UK, the Labour Party and the Liberal Democrats use it to elect their leaders. It is often abbreviated as AV.
Under the system voters rank candidates in order of preference.
Voters put a ‘1’ by their first choice, a ‘2’ by their second choice, and so on, until they no longer wish to express any further preferences.
Candidates are elected outright if they gain more than half of the first preference votes. If not, the candidate who got the least first preference votes is eliminated and the second preferences of their voters are added to the overall total. This process continues until one candidate has half of the votes and is elected.
In a UK-wide referendum in 2011, the British public were asked if they wanted to replace First Past The Post with the Alternative Vote for UK general elections. The referendum produced a No vote against AV.