Alliance

Allies Day, May 1917, National Gallery of Art
Field Marshal Bernard Montgomery decorates Soviet Marshals and generals at the Brandenburg Gate in Berlin, 12 July 1945.

An alliance is a relationship among people, groups, or states that have joined together for mutual benefit or to achieve some common purpose, whether an explicit agreement has been worked out among them. Members of an alliance are called allies. Alliances form in many settings, including political alliances, military alliances, and business alliances.