The signing of the Magna Carta in 1215 is significant because it established the principle that everyone, including the king, is subject to the law. This document, forced upon King John of England by rebellious barons, introduced fundamental rights such as due process and the right to a fair trial. It laid the groundwork for modern democracy by limiting monarchical power and asserting that rulers must govern in accordance with established laws. The Magna Carta has become a symbol of liberty and justice, influencing democratic principles and constitutional law across the world.