3.The Dark Web: Now this is something majority of people are unaware of, The Dark Web (also called Darknet) - a subset of the Deep Web that is not only not indexed, but that also requires something special to be able to access it, ex. specific proxying software or authentication to gain access( like TOR ). These pages require additional sub-network like Freenet ,I2P , TOR. Thes and is often associated with criminal activity of various degrees, including buying and selling drugs, gambling, etc. Have you heard of SILK ROAD , it was started in .onion sites only.