Ad to vote yes for the Treaty of Lisbon, by the Irish government, in 2009.

A plebiscite or referendum is a type of voting, or of proposing laws. Some definitions of 'plebiscite' suggest that it is a type of vote to change the constitution or government of a country. Others define it as the opposite. Australia defines 'referendum' as a vote to change the constitution and 'plebiscite' as a vote that does not affect the constitution.

There are two types of result

• Mandatory - meaning the government must do what the result says
• Advisory - meaning the result of the vote is only to help the government make the final choice.