Hello!!
The Magna Carta was a document that was created by the people King John ruled over. He was forced to sign it by his people and that signature basically said that if you sign (which he had to) we gets rights of stuff like what we would call today due process, and equal rights and all that fun stuff.
Continuously, the Magna Carta was in a way, renewed I guess? (sorry don't know if that's the right word.) On the original copy of the Magna Carta, it said that the document would only be enacted for 12 weeks. After King John died however, the people changed the document from 12 weeks to pretty much forever.
Hope that this helped. I honestly don't know if this is 500 words but i know that this is at least 200. So if you want a longer answer then wait for someone else's or pair mine up with someone else's.