A monarch (see sovereignty) is a type of ruler or head of state. Monarchs almost always inherit their titles and are rulers for life; that is, they have no term limit. Historically monarchs have been more or less absolute rulers. Modern monarchs are often figureheads who either have power but do not exercise it personally, or have little power. However, there are others with substantial or absolute power. Monarchs usually represent a larger monarchical system which has established rules and customs regarding succession, duties, and powers. A nation ruled by a monarch is called a monarchy. Those arguing against the concept of Monarchy are often, but not always, republicans.
The word "monarch" derives from Greek monos archein, meaning "one ruler," and referred to an absolute ruler in ancient Greece. With time, the word has been succeeded in this meaning by others, like autocrat or dictator, and the word monarch in modern usage almost always refers to a traditional system of hereditary rulership (but see the discussion on elective monarchies below).