Imperialism is when one country uses its power to take over a foreign country that has been around for centuries.
For instance Great Britain took over India. India was stronger back then and had a good trading system. Then someone attacked then and they were weaker than ever. The British then came in at the weak time and took over India. The British were well organized and had good strategy plans for attacking India. The French also tried to take over India but they got distracted from what they were doing. So Great Britain took this opportunity to go and take over the rest of India and kick out the French. India had a very weak navy so they couldn't really stand and fight. They would have to try to find a different want to take back their land and people.
Another instance is when Great Britain took over Australia. The reason Great Britain went and took over Australia was because Great Britain had so many prisoners that they had to take then somewhere else. They started taking them to the U.S. but after a while the U.S. wouldn't take them anymore because there was so many and they didn't want anymore bad people in their country coming over. So Great Britain decided to go to different places and drop off some prisoners, once the got to Australia they said no that they didn't want them in their cities and jails. Well the British got mad and decided to take over Australia so then they could do whatever they wanted with the people and the place. If they couldn't take over Australia then they had big problems. Great Britain was becoming more and more violent and the crime rates were increasing by the minute. They had to do something soon and fast.
The third instance was when the U.S. took over Hawaii. Hawaiians monarchy was over thrown by a group of business men and some sugar planters. They forced Queen Liliuokalani to abdicate. This lead to the dissolving of the Kingdom of Hawaii two years later. The U.S. saw an opportunity and decided that when Hawaii was weak they take it over. Some kings rose up to try and take back Hawaii and still have it be a monarchy but they failed in doing so. The United States eventually took Hawaii over it became the 50th state in America.
The fourth and final instance was when France took over Haiti. Haiti was in a big earthquake and they had to spend lots of money to rebuild their city and everything that was damaged. Australia, Brazil, Norway, Columbia and Estonia all helped with getting some money to rebuild their destroyed cities. Well Haiti had helped pay a debt for France and so France thought why not pay them back and help out. France was still deciding on what to do and Haiti was kind of getting impatient. France then had the idea of taking over Haiti so then it was their country now. Then this way France only had to worry about themselves and then there wouldn't be so much trading whatnot. The down fall to this idea was that once they took over Haiti they would have to pay back Australia, Brazil, Norway, Columbia, and Estonia. That would then cause some debt and create a few more problems. But they knew they could handle it all so they took over Haiti anyways.