There is a good explanation of the Magna Carta at the British Library's website. While Magna Carta is often held up as being the foundational text of the British Constitution, a more realistic view was expressed by Lord Sumption (Justice of the Supreme Court) who gave a speech last week. He said, "There are no high flown declarations of principle" in the Charter. He highlighted the "feeling of English exceptionalism especially in matters constitutional" (evident in David Cameron today lauded the document for "[shaping] the world for the best part of a millennium helping to promote arguments for justice and freedom"). Lord Sumption, a self-confessed "Magna Carta sceptic", argues that only two constitutional principles of note are evident in it: the idea of representation and the subjugation of the king to the rule of law. Misplaced are the notions that key aspects of our modern legal system (trial bu jury, for example) date back to the Magna Carta.
There's one aspect though that has struck me as interesting, concerning how different jurisdictions and societies display their key legal documents. The location of the Magna Carta, often held up as a foundational text for the British Constititution, is not particularly well-known: here are the locations of the originals and copies. Contrast the British approach with the key documents of the US Constitution: the Declaration of Independence, the Constitution, and the Bill of Rights. All are displayed proudly in the Rotunda for the Charters of Freedom in Washington, free for all to see in the National Archives Museum.