Federation

Political union of partially self-governing territories under a national government

A federation (also called a federal state) is a union of partially self-governing provinces, states, or other regions under a federal government (federalism). In a federation, the self-governing status of the component units and the division of power between them and the central government are constitutionally entrenched and may not be altered unilaterally by either the central or constituent-unit authorities without following the constitutional amendment process. Sovereign power is formally divided between a central authority and a number of constituent regions so that each region retains some degree of control over its internal affairs.

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