From the eighteenth century until the 1950s the British Empire was the biggest political entity in the world. The territories forming this empire ranged from tiny islands to vast segments of the world's major continental land masses. The British Empire left its mark on the world in a multitude of ways, many of them permanent. In this Very Short Introduction, Ashley Jackson introduces and defines the British Empire, reviewing its historiography by answering a series of key questions: What was the British Empire, and what were its main constituent parts? What were the phases of imperial expansion and contraction and the general causes of expansion and contraction? How was the Empire ruled? What were its economic effects? What were the cultural implications of empire, in Britain and its colonies? What was life like for people living under imperial rule? What are the legacies of the British Empire and how should we view its place in world history?