JHU encryption expert Matthew Green sheds light on the Deep Web

In the wake of last week's high-profile shutdown of online drug marketplace Silk Road, Johns Hopkins cryptography Professor Matthew Green spoke with The Baltimore Sun about some unfamiliar Internet terms, including Bitcoin, Tor, and the "Deep Web."

Green's explanations will help even the most casual Internet user understand the hidden side of cyberspace.

He starts by explaining what, exactly, is meant by the term Deep Web:

The Deep Web means two things. In some cases it's used to refer to the part of the web that isn't reached by search engines. Second, and more relevant to this case, it refers to a series of web sites that are only accessible through the Tor anonymity service.

Tor is software that routes your web connections through a number of other web servers—possibly around the world—in order to hide the source and destination of the connection. Typically you use Tor to access normal web sites, with the guarantee that the website can't trace you. However Tor also allows the destination web site to be in an anonymous location, also known as a "Tor Hidden Service."