A monarchy is a form of government in which a person, the monarch, is head of state for life or until abdication. The political legitimacy and authority of the monarch may vary from restricted and largely symbolic (constitutional monarchy), to fully autocratic (absolute monarchy), and can span across executive, legislative, and judicial domains.
The succession of monarchs in many cases has been hereditical, often building dynastic periods. However, elective and self-proclaimed monarchies have also been established throughout history. Aristocrats, though not inherent to monarchies, often serve as the pool of persons to draw the monarch from and fill the constituting institutions (e.g. diet and court), giving many monarchies oligarchic elements.
Monarchs can carry various titles such as emperor, empress, king, and queen. Monarchies can form federations, personal unions and realms with vassals through personal association with the monarch, which is a common reason for monarchs carryin