The Magna Carta has long been considered the foundation stone of the British Constitution, yet few people today understand either its contents or its context. This Very Short Introduction introduces the document to a modern audience, explaining its origins in the troubled reign of King John, and tracing the significance of the role that it played thereafter as a totemic symbol of the subject's right to protection against the raw and absolute authority of the sovereign. Drawing upon the great advances that have been made in the past two decades in our understanding of thirteenth-century English history, Nicholas Vincent demonstrates why the Magna Carta continues to be of enormous popular interest.