Anarchism is a political philosophy and movement that rejects all involuntary, coercive forms of hierarchy. It radically calls for the abolition of the state which it holds to be undesirable, unnecessary, and harmful. The history of anarchism stretches back to prehistory, when humans lived in anarchistic societies long before the establishment of formal states, realms or empires.
With the rise of organised hierarchical bodies, skepticism toward authority also rose, but it was not until the 19th century that a self-conscious political movement emerged. During the latter half of the 19th and the first decades of the 20th century, the anarchist movement flourished in most parts of the world and had a significant role in worker's struggles for emancipation. Various anarchist schools of thought formed during this period.