Throughout history, many countries have wanted to control or dominate territories beyond their borders. This practice is called imperialism, and the set of controlled territories is called an empire. Sometimes the leader of an empire is called an emperor. Countries build empires primarily to gain power and wealth.
Sometimes a ruler builds an empire by exercising dominion over nearby territories. In antiquity, the Roman Empire was one of the best known of its kind. The Romans spread their power from the city of Rome to territories in Europe, North Africa and western Asia.
An empire can also consist of territories far from the country that controls them. Sometimes, a country sends people to live in other lands, abroad. The settlements they establish are called colonies. In the 17th century, for example, England sent people to North America for the purpose of establishing colonies in the east of the continent. These colonies eventually became the United States.
Imperialism had a great influence on world history. Many imperial powers built roads, schools and hospitals in their colonies, but at the same time they abused the natural resources of those places. Imperialism also spread the culture of the colonizers. In many places that were once a colony, people still speak the language and practice the religion brought by the imperial power. For example, during the colonization of America, Europeans spread Christianity and languages like Portuguese and Spanish among the natives.
