Don't they need a proxy list to keep it anonymous? If not, how does it work? Do proxy sites just use their server ip to surf the web?
They just download the website at their end, and forward it onto your browser. So as far as your ISP knows - you have only visited the proxy website. It doesn't know what you have looked at through the proxy. This is a good way for testing websites through firewalls and from different countries etc...
proxy sites enable you to by pass your own internet provider & browse through the proxy web site. All that you have to do is type the web site address you would like to visit in the form they provide & start browsing.