The document discusses the 2011 UK referendum on adopting the Alternative Vote (AV) system to elect members of parliament. It provides background on nationwide referendums in the UK, and notes the referendum question asked voters if the current first-past-the-post system should be replaced with the alternative vote. It then outlines that the document will explain how the AV system works, why it was proposed, and that it was ultimately rejected by UK voters in the 2011 referendum.