Deep Web
What Is the Deep Web?
The deep web is the part of the internet that is not indexed by standard search engines, such as Google, Bing, and DuckDuckGo.
It sits behind the "surface web," which is the visible, searchable layer that most people browse every day. For this reason, the deep web is sometimes called the "hidden web" or "invisible web." Much of it is made up of ordinary content that simply is not designed to appear in search results.
How the Deep Web Differs From the Surface Web
The surface web is the most easily accessible layer of the internet and includes all pages that search engines can index. A frequently cited
2001 study estimated that less than 0.05% of online content was available on the surface web, while the remainder sat in the deep web. Although the exact proportion varies by source and has changed over time, the deep web is widely understood to be far larger than the surface web.
The deep web includes pages that either require a direct URL to reach or sit behind an authentication step. In practice, this covers many everyday services: email inboxes, social media profiles, online banking, and other password-protected accounts. It also includes large private databases and statistics maintained by organizations such as government agencies, including the US
Securities and Exchange Commission (SEC).
Deep Web vs. Dark Web
The deep web is often confused with the dark web, but they are not the same. The dark web is a small portion of the deep web that is intentionally kept hidden and is only reachable through specialized software. It is frequently associated with marketplaces and forums linked to illegal activity, including those used by malicious
hackers.
By most estimates, the dark web accounts for a very small fraction of the deep web. Understanding this distinction is helpful: the vast majority of the deep web is made up of routine, legitimate content that is simply not indexed, rather than anything hidden for illicit purposes.