Deep web

Content of the World Wide Web that is not indexed by search engines

The deep web, also known as the invisible web or the hidden web, is the parts of the World Wide Web whose contents are not indexed by standard web search-engine programs. This is in contrast to the surface web, which is accessible to anyone using the Internet. Computer scientist Michael K. Bergman is credited with inventing the term in 2001 as a search-indexing term.

From Wikipedia, under CC BY-SA. More on occurri.