Anarchism is a political philosophy and social movement that is skeptical of the justification of authority and power. It is grounded in moral claims about the importance of individual liberty, often conceived as freedom from domination. The term "anarchism" comes from the Ancient Greek "anarkhia," meaning "without a ruler". Anarchists oppose all systems of domination and oppression, such as racism, sexism, capitalism, and the state, and promote direct democracy, collaboration, interdependence, mutual aid, diversity, peace, transformative justice, and equity.

Anarchism is a process whereby authority and domination are replaced with non-hierarchical, horizontal structures, with voluntary associations between human beings. The ideal of anarchism is a society in which all individuals can do whatever they choose, except interfere with the ability of other individuals to do what they choose. This ideal is called anarchy, meaning absence of government. Anarchism is a utopian project that aspires to combine the best parts of liberalism with the best parts of communism.

Anarchism has inspired practical efforts at establishing utopian communities, radical and revolutionary political agendas, and various forms of direct action. Anarchists believe that societies can be organized in a way that allows for the maximum amount of individual freedom and equality. Anarchism is a philosophy that embodies many diverse attitudes, tendencies, and schools of thought, and disagreement over questions of values, ideology, and tactics is common.