Centralization is a government organization by which power is vested in the central government, and is exercised at the local level when explicitly delegated by the central government. Centralized federalist governments are those where powers are defined constitutionally to be exercised at the local level, but those not explicitly restricted only to local governance are the prerogative of the central government. Centralization can be contrasted with subsidiarity, where powers not delegated to the central government are reserved to local governance.