The significance of the Magna Carta, signed in 1215, lies in its establishment of the principle that everyone, including the king, is subject to the law. It was a landmark document that limited the powers of the monarchy and laid the groundwork for individual rights and due process. The Magna Carta introduced concepts such as the right to a fair trial and protection from unlawful imprisonment. Its influence extended beyond England, inspiring constitutional frameworks in various democracies, and is often cited as a foundational stone for modern legal systems and human rights principles.