• Sovereignty is the exercise of power over a given territory.
• Authority is the ability to exercise power, meaning that sovereign authority is the ability to exercise power over a given territory.
• Legitimacy is the normative recognition that someone should have authority over a given territory.

States may have a combination of sovereignty, legitimacy, and authority. A state may be a legitimate and sovereign authority if most actors within and outside the state recognize its ability and deservingness to rule over its territory. A government in exile may be recognized as the legitimate ruler of a territory, though they may not exercise any real power over their former country and therefore lack sovereign authority.