Anarchy is the condition of a society, entity, group of people, or a single person that rejects hierarchy. The word originally meant leaderlessness, but in 1840 Pierre-Joseph Proudhon adopted the term in his treatise What Is Property? to refer to a new political philosophy: anarchism, which advocates stateless societies based on voluntary associations. In practical terms, anarchy can refer to the curtailment or abolition of traditional forms of government and institutions. It can also designate a nation (or anywhere on earth that is inhabited) that has no system of government or central rule. Anarchy is primarily advocated by anarchists, individuals who propose replacing government with voluntary institutions.
The word anarchy comes from the ancient Greek ἀναρχία (anarchia), which combines ἀ (a), "not, without" and ἀρχή (arkhi), "ruler, leader, authority." Thus, the term refers to a person or society "without rulers" or "without leaders".