deep web
termdark webprivacy
Everything on the web that search engines do not index, which is most of it.
The deep web is mundane and enormous: your webmail inbox, banking portal, paywalled journals, and any page behind a login or a query form. The persistent confusion is treating it as sinister, when it simply means not crawlable. The dark web is a tiny, deliberately hidden subset of it, reachable only with specific software, and conflating the two makes ordinary private pages sound like a crime scene.
Also known as: invisible web, hidden web