Kings are hereditary sovereigns when they hold the powers of government by right of birth or inheritance, and elective when raised to the throne by choice.
The Common Germanic term was borrowed into Estonian and Finnish at an early time, surviving in these languages as kuningas.
The monarchies of Europe in the Christian Middle Ages derived their claim from Christianisation and the divine right of kings, partly influenced by the notion of sacral kingship inherited from Germanic antiquity.
With the breakup of the Carolingian Empire in the 9th century, the system of feudalism places kings at the head of a pyramid of relationships between liege lords and vassals, dependent on the regional rule of barons, and the intermediate positions of counts (or earls) and dukes.
By the end of the Middle Ages, the kings of these kingdoms would start to place arches with an orb and cross on top as an Imperial crown, which only the Holy Roman Emperor had had before.