Imperialism is a type of advocacy of empire. Its name originated from the Latin word "imperium", which means to rule over large territories. Imperialism is "a policy of extending a country's power and influence through colonization, use of military force, or other means". Imperialism has greatly shaped the contemporary world. It has also allowed for the rapid spread of technologies and ideas. The term imperialism has been applied to Western (and Japanese) political and economic dominance especially in Asia and Africa in the 19th and 20th centuries. Its precise meaning continues to be debated by scholars. Some writers, such as Edward Said, use the term more broadly to describe any system of domination and subordination organised with an imperial center and a periphery. 

Imperialism is defined as "A policy of extending a country’s power and influence through diplomacy or military force." Imperialism is particularly focused on the control that one group, often a state power, has on another group of people. This is often through various forms of "othering" (see other) based on racial, religious, or cultural stereotypes. There are "formal" or "informal" imperialisms. "Formal imperialism" is defined as "physical control or full-fledged colonial rule". "Informal imperialism" is less direct; however, it is still a powerful form of dominance.
and infromal?
"Informal imperialism" is less direct; however, it is still a powerful form of dominance