Web-based that can be indexed by search engines like Google and Yahoo. The articles you can read on Fhm.com.ph, for example, are on the surface web.
Web-based content that are coded so they can’t be indexed by search engines. The Deep Web is way bigger than the surface web, and it isn’t as nefarious as you might think it is—a large chunk of what you’ll find there are image galleries, staging websites, unpublished content, or archived pages. The backend of Fhm.com. ph? Part of the deep web. The spreadsheet you made on Google Sheets? Also part of the deep web. Same goes for pages that can only be accessed during a specific timeframe or via a unique URL, like Wetransfer.com download links. It’s mostly harmless, really.
This is the underbelly of the deep web, where all the scary stuff happens. Dark websites can only be accessed by special software that let users surf in total anonymity—which is very important, because you never know who might be watching you over there.