What web technology have been used on http://ift.tt/1RZDmzJ

I was browsing Bad Assembly website: http://ift.tt/1RZDmzJ and I saw something really interesting on it.

When you scroll through different sections it changes the URL in address bar and also browser "Back" button is active and that happens without a page refresh.

Can anyone tell me how was it achieved? Is there any framework for this. I just want to know so I can learn about it.