The history of nationalism can be traced back to the 18th century when it began to emerge as a form of political and social ideology. It was influenced by the American and French revolutions, which emphasized the importance of nationhood, as well as the Romantic movement, which focused on the power of communal identity and belonging. The 19th century saw the rise of the nation-state and the idea of self-determination and the gradual formation of modern nations. Nationalism was later used as a tool to legitimize colonialism and imperialism, which has had a lasting and profound impact on the world to this day. In the 20th century, nationalist movements gained strength from the concept of self-determination, and today nationalism is a major force in international politics.