The term used for the policy of extending a country's power and influence through colonization is **imperialism**. This approach dominated global politics, particularly from the 19th century to the early 20th century. European powers, along with the United States and Japan, expanded their territories and exerted control over vast regions in Africa, Asia, and the Pacific, often through military conquest or diplomatic pressure. Imperialism not only molded the political landscapes of colonized nations but also led to significant economic exploitation and cultural assimilation, with lasting effects on global relations.