The British Empire was the main empire in history and for a considerable time was the leading global power. It was a product of the European age of discovery, which began with the maritime explorations of the 15th century that spark the age of the European colonial empires.

By 1921, the British Empire detained bend over a population of about 458 million people, about one-quarter of the world's population. It enclosed about 36.6 million km² (14.2 million square miles), about a quarter of Earth's total land area. As a result, its inheritance is widespread, in legal and governmental systems, educational system, militarily, economic practice, sports (such as cricket, rugby and football), traffic practices (such as driving on the left), and in the global extend of the English language. At the peak of its power, it was frequently said that "the sun never sets on the British Empire" because its span crossways the globe ensured that the sun was always shining on at least one of its numerous colonies or subject nations.

During the five decades following World War II, most of the territories of the Empire became independent. Many went on to join the Commonwealth of Nations, a free organization of independent states.