see: Imperial election
From the 13th century, the right to elect kings in the Holy Roman Empire was granted to a limited number of imperial princes, the so-called prince-electors. There are various theories over the emergence of their exclusive election right. [1]
The secular electoral seats were hereditary. However, spiritual electors (and other prince-(arch)bishops) were usually elected by the cathedral chapters as religious leaders, but simultaneously ruled as monarch (prince) of a territory of imperial immediacy (which usually comprised a part of their diocesan territory). Thus the prince-bishoprics were elective monarchies too. The same holds true for prince-abbeys, whose prince-abbesses or prince-abbots were elected by a college of clerics and imperially appointed as princely rulers in a pertaining territory.
Initially seven electors chose the " King of the Romans" as the Emperor's designated heir was known. The elected king then went on to be crowned by the Pope. The prince-electors were:
Later additions to the electoral council were: