Metal Gear Solid (MGS4) PS3 STORY?

So i got MGS4 many people have told me its a beautiful and mazaing game to play but before i play it i just wanted to know if i needed to know the story of the other MGS games to understand this one...and if i do then maybe can u give me a website that tells me the storys or briefly tell me what is going on in the others so i know what is happeneing in this game.