The deep web is sometimes known as the invisible web or the hidden web, but whatever you call it, it’s about those hidden parts of the Internet that you can’t reach just by using the usual array of search engines like Google, Yahoo, or Bing. They’re only good for finding pages on the surface web, whereas deep web information is not publicly available.
Wikipedia is an example of a website that’s on the surface web. You can easily find pages there using run-of-the-mill search engines. But when information isn’t in the public domain or access to it is restricted, it’s part of the deep web. Deep web examples could include Amazon Prime, where streaming videos are only shared with subscribers, OneDrive, where files stored in the cloud are only accessible by authorized individuals, or any financial services website where data is only shared with account holders.
Typical search engines like Bing will frequently add details of new Internet content to their index, and this information is what helps keep their search results fresh so that when users search for particular key terms, they are handed a reliable list of the most relevant and up-to-date matches. But deep web content isn’t picked up by the indexing process because it’s protected from public view.