Some academic writers discuss states and governments in terms of "models".
An independent nation state normally has a head of state, and … See more

In a republic, the head of state nowadays usually bears the title of President, but some have or have had other titles. Titles commonly used by … See more

Whenever a head of state is not available for any reason, constitutional provisions may allow the role to fall temporarily to an assigned person or … See more

Since antiquity, various dynasties or individual rulers have claimed the right to rule by divine authority, such as the Mandate of Heaven and the divine right of kings See more

Head of state is the highest-ranking constitutional position in a sovereign state. A head of state has some or all of the roles listed below, often depending on the constitutional … See more

• The polis in Greek Antiquity and the equivalent city states in the feudal era and later, (many in Italy, the Holy Roman Empire, … See more

In early modern Europe, a single person was often monarch simultaneously of separate states. A composite monarchy is a retrospective label for those cases where the states were governed entirely separately. Of contemporary terms, a personal union See more