A federation is a state comprised of a number of self-governing regions (often themselves referred to as states) united by a central (federal) government. In a federation the self-governing status of the component states is constitutionally entrenched and may not be altered by a unilateral decision of the central government. Federations may be multi-ethnic, or cover a large area of territory, although neither is necessarily the case. Federations are often founded on an original agreement between a number of sovereign states. The component states of a federation usually do not have the right to secede unilaterally .
A federation is distinct from a state which is composed of self-governing regions but in which the autonomous status of those regions exists at the sufferance of the central government, and may be unilaterally revoked. Such a state is a form of unitary state. Spain and Belgium are examples of unitary states that are superficially federal in structure. A federation is further to be distinguished from:
A confederation: an entity similar in structure to a federation but with a weaker central government. A confederation may consist of states that are considered sovereign and that retain the right of secession (one possible example being the European Union).
An empire: a multi-ethnic state with a political structure established through coercion.
The Russian Federation is not a true federation in the strict sense. It consists of the metropolis of Russia proper, which includes the great majority of the population and is governed by the national government in Moscow, and a number of small ethnic enclaves, which are known as Autonomous Republics or Autonomous Oblasts, but which possess very little actual autonomy.
The European Union possesses some of the attributes of a federal state but its central government is weaker than that of most federations. Furthermore, its member states are separate entities under international law and, currently at least, possess a de facto if not explicit de jure right of secession.
In Australian history, 'Federation' refers to the formation of the Commonwealth of Australia by six British colonies on 1 January 1901, and also to the political movement in the 1890s to bring this about.
