De jure simply means 'in law'; literally 'regarding law'. According to law, the Queen is Head of State in the Commonwealth realms and in the United Kingdom. De facto means 'in fact', that is, 'for all practical purposes', but not accordingly to law. A de facto head of state would be one who governs practically but without due process of law, such as the leader of a coup or a usurper. Even when a country is presided over by a person acting as a regent, such as the Prince Regent George who became George IV, or a Governor-General in the Commonwealth Realms, the reigning Sovereign remains de jure Head of State. Please let us not resurrect the awful discussion about who is Elizabeth really Queen of. It took up pages and created a lot of heat and bad feeling.