A confederation (also known as a confederacy or league) is a political union of sovereign states united for purposes of common action. Usually created by a treaty, confederations of states tend to be established for dealing with critical issues, such as defence, foreign relations, internal trade or currency, with the central government being required to provide support for all its members. Confederalism represents a main form of intergovernmentalism, defined as any form of interaction around states that takes place on the basis of sovereign independence or government.
The nature of the relationship among the member states constituting a confederation varies considerably. Likewise, the relationship between the member states and the general government and their distribution of powers varies. Some looser confederations are similar to international organisations while other confederations with stricter rules may resemble federal systems.These elements of such confederations, the international organization and federalist perspective, has been combined as supranational unions.