Deep Web or Hidden Web or Invisible Web or Encrypted Web is used to refer to those websites that are not indexed by any search engines and which need layers of encryption to be visited.
Surprisingly, only 4% of Web Content (Approximately 8 billion pages) is available via Search Engines. The rest 96% of the digital universe is on Deep Websites protected by passwords. It is said that the hidden web is 500 times larger than the visible or surface web.