Take A Tour Of Silk Road, The Online Drug Marketplace The Feds Shut Down Today
The Silk Road operated on the Tor network, an anonymous collection of sites that exist in semi-secrecy, outside of the scope of Google, Facebook, and even conventional web browsers.
This network is designed in such a way that all your activity on it is kept completely anonymous and untraceable.
When you pair this with Bitcoin, an anonymous digital currency that can be converted into real money, it's plain to see how Silk Road could not only operate, but thrive.
Until today, of course.
For the rest of the story: http://www.businessinsider.com/silk-road-walkthrough-2013-10?op=1