In a situation where no single political party wins an overall majority after the polls close at 10pm tonight (7 May), the 2015 General Election will be known as a ‘hung Parliament’.
Under the current electoral system, First Past The Post (FPTP) the candidate in each of the 650 constituencies with the most votes wins, thus a party needs 326 elected MPs for an outright majority.
In the case of a hung Parliament, the current Government will remain in place until a majority government can be formed - which is what happened in the 2010 General Election.
Talks between party leaders could take days as agreements are brokered ensuring a new administration can function.
This could mean party manifestos that people voted for could be altered or cast aside.
Or, a party leader could opt to go it alone and try to run a minority government.
In that scenario they would still need the support of other parties in order to get their laws passed.
There is only one guideline for forming a government in a hung Parliament: that the politician who can tell the Queen that he has a workable majority in the House of Commons is the one the Queen will authorise to form a government.