What was the Mayflwoer Compact?

Damn, I know the Mayflower was a ship how they came to America but I am not quite sure about the Mayflower Compact. I think it was a treaty signed with the Indians but I am not sure. I am hitting the history books tonight though because not knowing this is very embaring wait.....I do think it was some thing about obaying all laws or something because they made up laws or something....I am changing my mind,....I am tipping 90% to C not sure though