AV is an alternative Voting System. In 2011 we had a referendum to see if it would replace First Past The Post.Read more
What is First Past the Post? (FPTP)
FPTP is the electoral system used to elect MPs to the House of Commons. FPTP is a plurality electoral system in which the winning candidate only needs one vote more than their leading opponent in order to win their seat.
The winning candidate does not need to achieve a majority of votes (50%+1) in their constituency. For example in 2010, Labour candidate Glenda Jackson won her seat in Hampstead and Kilburn with only 32.8% of the vote.
If one party is able win at least 50% of the seats in the House of Commons (326 out of a total 650) then its leader gets to become prime minister and form a government.