Key points are not available for this paper at this time.
The terms Deep Web, Deep Net, Invisible Web, or Dark Web refer to the content on the World Wide Web that is not indexed by standard search engines. One can describe the Internet as composed of layers: the “upper” layer, or the Surface Web, can easily be accessed by regular searches. However, “deeper” layers, the content of the Deep Web, have not been indexed by traditional search engines such as Google. Michael K. Bergman who wrote the seminal paper on the Deep Web, compared searching the Internet to dragging a net across the surface of the ocean: a great deal may be caught in the net, but there is a wealth of information that is deeper and therefore missed. In fact, most of the Web's information is buried far down on sites, and standard search engines are unable to access it.
Gabriel Weimann (Wed,) studied this question.