Anarchism is a political philosophy and movement that is against all forms of authority and seeks to abolish the institutions it claims maintain unnecessary coercion and hierarchy, typically including the state and capitalism. Anarchism advocates for the replacement of the state with stateless societies and voluntary free associations. As a historically left-wing movement, this reading of anarchism is placed on the farthest left of the political spectrum, usually described as the libertarian wing of the socialist movement.

Anarchism and violence have been linked together by events in anarchist history such as violent revolution, terrorism, and assassination attempts. Leading late 19th century anarchists espoused propaganda by deed, or attentáts, and was associated with a number of incidents of political violence. Anarchist thought, however, is quite diverse on the question of violence. Where some anarchists have opposed coercive means on the basis of coherence, others have supported acts of violent revolution as a path toward anarchy. Anarcho-pacifism is a school of thought within anarchism which rejects all violence.

The International Conference of Rome for the Social Defense Against Anarchists was held between 24 November and 21 December 1898 following the assassination of Empress Elisabeth of Austria by Luigi Lucheni on the promenade of Lake Geneva on 10 September 1898. Fifty-four delegates attended from 21 countries. Every participating government agreed to set up special organizations for the surveillance of those suspected of anarchism, defined as "any act that used violent means to destroy the organization of society."

Anarchism in Greece traces its roots to ancient Greece but was formed as a political movement during the 19th century. It was in the ancient era that the first libertarian thoughts appeared when philosophers based on rationality questioned the fundamentals of tradition. Modern anarchism in Greece emerged in the 19th century, heavily influenced by the contemporary European classical anarchism. Because of the Bolshevik success in the Russian Revolution of 1917 and the rise of the Communist Party, anarchism faded after the first decades of the 20th century. The collapse of the military junta put an end to the monopoly of the political power from the Right, whereas the dissolution of the Soviet Union diminished the allure of the Communist Party of Greece allowing anarchist groups to gain pace in Athens and other cities.

Far-left politics, also known as extreme left politics or left-wing extremism, are politics further to the left on the left–right political spectrum than the standard political left. The term does not have a single, coherent definition; some scholars consider it to be the left of communist parties, while others broaden it to include the left of social democracy. In certain instances—especially in the news media—far left has been associated with some forms of authoritarianism, anarchism, communism, and Marxism, or are characterized as groups that advocate for revolutionary socialism and related communist ideologies, or anti-capitalism and anti-globalization. Far-left terrorism consists of extremist, militant, or insurgent groups that attempt to realize their ideals through political violence rather than using democratic processes.

Mark J. Sedgwick is a British historian of Islam. He is Full Professor of Arab and Islamic Studies at Aarhus University in Denmark. Sedgwick is notable for pioneering historical research into the religious movement called Traditionalism.

Insurrectionary anarchism is a revolutionary theory and tendency within the anarchist movement that emphasizes insurrection as a revolutionary practice. It is critical of formal organizations such as labor unions and federations that are based on a political program and periodic congresses. Instead, insurrectionary anarchists advocate informal organization and small affinity group based organization. Insurrectionary anarchists put value in attack, permanent class conflict and a refusal to negotiate or compromise with class enemies.