Anarchism is a political philosophy advocating the removal of the State and the establishment of a society without government. The term is of Greek origin, meaning "without rulers".
Old anarchist thought is similar to traditional Communist thought (though not practice) in that it rejects all authority. However, individualist anarchists and anarcho-capitalists are ideologically closer to libertarianism than Communism, however most anarchists of the communist type reject these as anarchists, as they consider them to be capitalists, and not anarchists. Some anarchists have been known to employ violent means in their endeavors, though many anarchists are non-violent. Some anarchist groups have been labeled by the U.S. government as terrorist organizations.
In addition to being a philosophy, anarchy can also be a description of a system in which there is no higher governmental authority. The world level of political interaction is considered anarchical, because there is no power over the sovereign states (i.e. there is no world government).