Imperialism was a country extending their power or wealth by conquering other countries with diplomacy or military force. Many European countries used the concept of Social Darwinism, especially when conquering the countries of Africa. The Europeans said "oh, look at those poor African natives! They're so primitive! By conquering them, we're helping them, because those natives are less evolved then we are, and as the superior beings, it's are duty to help them become more "civilized". You see? Europeans used the excuse that the people of the countries they were conquering were less civilized and that Europe was "saving" these native people.