The Commonwealth of Australia is a constitutional monarchy with a parliamentary system and is based on the Westminster model. The term Opposition has a specific meaning in the parliamentary sense, with a formal title of Her Majesty's Loyal Opposition. It is an important component of the Westminster system, with the Opposition directing criticism at the Government and attempts to defeat and replace the Government. The Opposition is therefore known as the 'Government in waiting' and it is a formal part of the parliamentary system. It is in opposition to the Government, but not to the Crown; hence the term 'Loyal Opposition'.