An alliance of countries, also known as a BLOC, is an agreement between two or more nations to cooperate in political, economic, and/or military matters. The term 'alliance of countries' is often used to refer to a group of nations that have formed a mutual defense pact, such as the North Atlantic Treaty Organization (NATO). It can also refer to a group of nations that have formed a trade agreement, such as the European Union (EU). In either case, the members of the alliance are bound by a common set of goals and objectives.