In general, allies are people, groups, or nations that've joined together in an association for mutual benefit or to achieve some common purpose. In English usage, those who share a common goal and whose work toward that goal's complementary may be viewed as allies for various purposes even when no explicit agreement has been worked out between them. Similarly, when the term's used in the context of war or armed struggle, a formal military alliance isn't required for being perceived as an ally… (More on Allied)