Decolonisation is the undoing of colonialism. Colonialism is a process of a nation establishing and maintaining its dominations of overseas territories. The concept of decolonisation, in particular, applies to the dismantlement of European colonies in Africa and Asia towards the second half of the 20th century.

The very core of decolonisation is the right to self-determination as a fundamental right identified by the United Nations, which paves the way for independence along with other methods of decolonization.

The United Nations Special Committee on Decolonization has stated that there is no other alternative for the coloniser but to allow a process of self-determination.

The process of decolonisation may involve nonviolent revolutions or violent revolutionary wars by pro-independence groups. It may be intranational like the Indian Independence Struggle or may involve the intervention of foreign powers as was the case during the liberation of Bulgaria when the Russian Empire intervened to free it from the Ottoman Empire.

Along with these examples, there have been cases of particularly active periods of decolonization during modern times such as the breakup of the Spanish Empire in the 19th century, Abolition of the Ottoman Empire post-World-War I, dismantlement of the British, French, Dutch and Japanese Colonial Empires after World War II and the dissolution of the Soviet Union at the end of the Cold War.