Short answers, pulled from the story.
The British Empire comprised the dominions, colonies, protectorates, mandates, and other territories ruled or administered by the United Kingdom and its predecessor states. By 1913 it held sway over 412 million people, and by 1920 it covered 35.5 million square kilometres of the Earth's land area. It was the largest empire in history and for a century the foremost global power.
The British Empire was described as "the empire on which the sun never sets" because the sun was always shining on at least one of its territories. The phrase reflected the empire's spread across the globe at its height in the 19th and early 20th centuries.
Britain became a major power in India after the East India Company defeated the Nawab of Bengal and his French allies at the Battle of Plassey in 1757, which left the company in control of Bengal. After the Indian Rebellion of 1857, Britain dissolved the company through the Government of India Act 1858 and ruled directly as the British Raj, with Queen Victoria crowned Empress of India.
British ships carried roughly 3.5 million Africans, about a third of all slaves shipped across the Atlantic, until Parliament abolished the trade in 1807. The Royal African Company, granted a monopoly in 1672, raised England's share of the trade from 33 per cent in 1673 to 74 per cent in 1683, and ships registered in Bristol, Liverpool and London carried the bulk of the trade.
India achieved independence on the 15th of August 1947, after the last Viceroy, Lord Mountbatten, brought the date forward. Partition into India and Pakistan left tens of millions as minorities in the newly independent states, and violence between the communities cost hundreds of thousands of lives.
The Suez Crisis of 1956 confirmed Britain's decline as a global power, and the handover of Hong Kong to China on the 1st of July 1997 symbolised for many the end of the British Empire. Fourteen overseas territories that are remnants of the empire remain under British sovereignty, and fifteen states including the United Kingdom still retain the same person as monarch.