Monarchy
Monarchy (from Greek "monarkhia" meaning "rule of one") is a form of government in which a single person, the monarch, has supreme authority or sovereignty.
History
Monarchy is usually described as hereditary, but there have been elected or self-proclaimed monarchs. The first monarch in a royal dynasty often did not inherit the position.
Ancient Greek philosophers described monarchy as one of the good forms of government, contrasted with tyranny.
One argument cited by supporters of monarchy, and especially hereditary monarchy, is that the monarch has a long-term personal interest in improving the country, in contrast with short-term rulers.
The actual power of a monarch may vary widely, from absolute monarchy / "absolutism" to purely ceremonial roles in some constitutional monarchies. Intermediate powers for a monarch, such as in some constitutional monarchies, may be influenced by views such that “mixed constitutions” are superior, combining aspects of monarchy, aristocracy, and democracy. Such views were not uncommon earlier, even having an influence on the American Founding Fathers, but are now often considered less politically correct.
"Monarchism" is ideological support for monarchy as a system. A "royalist" is a supporter of a particular monarch, often in the context of this monarch being threatened to be deposed, or to have been recently deposed, by anti-monarchists.