Imperialism is where a Country WIth more power takes over another country or region
World War 2 is one of the many times imperialism has happened. With germany wanting to take over all of Europe and Germany killing over 6 million jews and more types of races. They wouldn't stop taking over. The same thing with japan coming in and taking over parts of china.
The U.S.A. Has around 800 milltary bases in over 70 countries This could be for many different reasons.
Russia trying to take over and have power over ukraine
Iran trying to gain power and make a empire