The term dark web is a general and rather imprecise term used to refer to sites and services that are not directly accessible on the internet. Access to such sites is typically only provided through gateway services or proxies. One common example would be sites that are only accessible using the TOR anonymizing service. These services are variously used to either control or restrict access, or to ensure the anonymity of both site ownership and location, as well as visitor identity.
Strictly speaking, if a site is directly accessible via an http or https connection it’s not considered to be on the dark web. Sites which have simply removed themselves from search engine results, but remain on the public internet, are classified by the equally general and imprecise term deep web.
The dark web is the World Wide Web content that exists on darknets: overlay networks that use the Internet but require specific software, configurations, or authorization to access. Through the dark web, private computer networks can communicate and conduct business anonymously without divulging identifying information, such as a user's location. The dark web forms a small part of the deep web, the part of the Web not indexed by web search engines, although sometimes the term deep web is mistakenly used to refer specifically to the dark web.
The darknets which constitute the dark web include small, friend-to-friend peer-to-peer networks, as well as large, popular networks such as Tor, Freenet, I2P, and Riffle operated by public organizations and individuals. Users of the dark web refer to the regular web as Clearnet due to its unencrypted nature. The Tor dark web or onionland uses the traffic anonymization technique of onion routing under the network's top-level domain suffix .onion.