An
alliance is a relationship among
people, groups, or
states that have joined together for mutual benefit or to achieve some common purpose, whether or not 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. When the term is used in the context of
war or armed struggle, such associations may also be called
allied powers, especially when discussing World War I or World War II.