Some academic writers discuss states and governments in terms of "models".
An independent nation state normally has a head of state, and determines the extent of its head's … 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 collective body. In a republic, this is - … 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 … 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, the Moorish taifa in Iberia, essentially tribal-type but urbanised regions throughout the world in the Maya civilisation 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 … See more