For a government to be republic, where does it's power have to come from

Republic, form of government in which a state is ruled by representatives of the citizen body. Modern republics are founded on the idea that sovereignty rests with the people, though who is included and excluded from the category of the people has varied across history.

Explanation: Because citizens do not govern the state themselves but through representatives, republics may be distinguished from direct democracy, though modern representative democracies are by and large republics. The term republic may also be applied to any form of government in which the head of state is not a hereditary monarch.