Deep Web

The deep web refers to secret sections of the Internet whose contents are not accessible through standard search engines like Google, Yahoo, or Bing.

Also called the hidden web or invisible web, the deep web is the opposite of the surface web, whose contents can be accessed through search engines.

For example, information on sites like Investopedia constitute part of the surface web, as it can be reached through search engines. Content that is not in the public domain and has limited access - like privately shared files through Dropbox, or sites accessible only through a secure login like financial transactions on online bank accounts or PayPal, or on-demand videos on Netflix - are part of the deep web.

Standard search engines like Google regularly scan the Internet for content and add the details to their index. This indexation method helps in displaying the search results that match the search query posted by a user searching the Internet for information. Any content that is indexed by search engine hence becomes available in the public domain through search engine results.

But deep web content is hidden behind secure access, which is limited to eligible individuals only, and may not be indexed and reached by regular search engines. (See also: What Is the Dark Net?)