A confederation (or confederacy), in modern political terms, is a permanent union of political units for common action in relation to other units. Usually created by treaty but often later adopting a common constitution, confederations tend to be established for dealing with critical issues (such as defense, foreign affairs, or a common currency), with the central government being required to provide support for all members.
The nature of the relationship among the states constituting a confederation varies considerably. Likewise, the relationship between the member states, the central government, and the distribution of powers among them is highly variable. Some looser confederations are similar to intergovernmental organizations, while tighter confederations may resemble federations.
In a non-political context, confederation is used to describe a type of organization which consolidates authority from other autonomous (or semi-autonomous) bodies. Examples include sports confederations or confederations of pan-European trades unions.
In Canada, the word confederation has an additional, unrelated meaning. "Confederation" refers to the process of (or the event of) establishing or joining the Canadian federal state.
In the context of the history of the indigenous peoples of the Americas, a confederacy may refer to a semi-permanent political and military alliance consisting of multiple nations (or "tribes", "bands", or "villages") which maintained their separate leadership. One of the most well-known is the Iroquois Confederacy, but there were many others during different eras and locations across North America; these include the Western Confederacy, Powhatan Confederacy, Seven Nations of Canada, Pontiac's Confederacy, Illinois Confederation, Tecumseh's Confederacy, Great Sioux Nation, Blackfoot Confederacy, Iron Confederacy, and Council of Three Fires.
Read more about Confederation: Historical Confederations