Head of State, or Chief of State, is a term used in constitutional law, international law, political science, and diplomatic protocol when referring to the official who holds the highest ranked position in a sovereign state and has the vested or implied powers to act as the chief public representative of a state. Heads of state in most countries are natural persons holding an office; however, in four United Nations member states the head of state position is held by a body of persons: the Federal Council of Switzerland, the Presidency of Bosnia and Herzegovina, the Co-Princes of Andorra and the Captains Regent of San Marino.
The term head of state is often used differentiating it from the term head of government, e.g. as in article 7 of the Vienna Convention on the Law of Treaties, article 1 of the Convention on the Prevention and Punishment of Crimes against Internationally Protected Persons, including Diplomatic Agents and the United Nations protocol list. For instance, in parliamentary systems like the United Kingdom of Great Britain and Northern Ireland and the Federal Republic of Germany; the Monarch and the President are recognized as their respective heads of state, while the Prime Minister and the Chancellor are recognized as the heads of government. However in republics with a presidential system, as in the United States and the Federative Republic of Brazil, their presidents are recognized as being both heads of state and heads of government. The latter is also generally true in absolute monarchies and sometimes as well in other forms of authoritarian government.