The extent of official recognition of national academies varies between countries. In some cases they are explicitly or de facto an arm of government; in others, as in the U.K, they are voluntary, non-profit bodies with which government has agreed to negotiate, and which may receive government financial support while retaining substantial independence. In the countries of the former Soviet Union, and in the People's Republic of China, the national academies have considerable power over policy and personnel in their areas.
In some countries, a single academy covers all disciplines; an example is the Académie française in France. In others, there are several academies, which work together more or less closely; for example, Australia has separate academies for the sciences, social sciences, and humanities. In the U.K., the Royal Society is recognised as the national academy for the sciences, the British Academy for the social sciences and the humanities, and the Royal Society of Engineering and the Royal Society of Medicine for their areas. In the United States, there are also four National Academies.
Within most countries, the unqualified phrase "National Academy" will normally refer to that country's academy. Within the United States, the plural phrase "National Academies" is widely understood to refer to the US National Academies.