The Deep Web is web-based content that is not found in search engine results. Unlike Darknets, wherein the content is explicitly encrypted and kept from public view, most of the Deep Web content is invisible to search engines and their users simply because there are no links pointing the content. For example, if you created a website and never published the individual URLs of the page or linked to them from a publicly accessible main page, the chances that a search engine would find and index those pages are next to zero.
It is estimated that the size of the Deep Web is thousands of times larger than the public Web (the portion of the Web indexed by search engines).
- By Jason Fitzpatrick on 05/10/13