What significant action did the Magna Carta accomplish?

The Magna Carta, signed in 1215, is a cornerstone of British history and legal tradition. Think of it as a really, really old contract between the King and his barons. Before the Magna Carta, the King had pretty much unlimited power. He could do whatever he wanted, whenever he wanted. The barons, fed up with excessive taxes and arbitrary rule, forced King John to agree to a set of written promises. The key thing is that the Magna Carta established the principle that everyone, including the King, was subject to the law. It restricted the King's power by guaranteeing certain rights and liberties to the barons, like the right to a fair trial. It didn't introduce Christianity – that happened much earlier with the Roman Empire and later with St. Augustine. It also didn't introduce democracy in the modern sense; that was a much longer process. And while the King still collected taxes after 1215, the Magna Carta aimed to ensure they were collected more fairly and with the consent of the barons. So, the most significant thing the Magna Carta did was limit the King's power, setting the stage for the development of parliamentary democracy and the rule of law in Britain.