Deep web
lastmod 2022-04-12created 2022-04-121 edits
The deep web (also invisible web, hidden web) refers to World Wide Web content that is not exposed by ordinary search engines and does not belong to the surface web. It is easy to think that the World Wide Web, often shortened to just the web, is the whole internet, but the internet consists of many services such as the World Wide Web, email, online games, file sharing (torrent, eMule, etc.), mobile apps, video streaming, webcams, and VoIP. Although the deep web has "web" in its name, it actually also includes services that are not the World Wide Web. Because it includes non-web services, the name deepnet is more accurate than deep web. The English Wikipedia redirects the deepnet article to deep web.
An overlay network that requires permission to access or can only be accessed with specific software is called a darknet. The term for only the web content of darknets is the dark web. Darknets and the dark web are part of the deep web, but the term deep web is often misused to refer to darknets or the dark web. Although darknet, like internet (a name derived from internetwork), has net (short for network) in its name, Tor, which in practice includes only web services, is generally counted as a darknet along with I2P and Freenet. The deep web includes darknets, and darknets include the dark web.
According to an experiment conducted at the University of California, Berkeley in 2001, the content of the deep web is about 7,500 terabytes. A more precise survey by Bin He et al. in 1999 found about 8,900,000 deep web sites, and Denis Shestakov found some 14,000 Russian deep web sites in 2006.