Dark web

The dark web is the World Wide Web content that exists on darknets, overlay networks which use the public Internet but require specific software, configurations or authorization to access. The dark web forms a small part of the deep web, the part of the Web not indexed by 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 like Freenet, I2P, and Tor, 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 may be referred to as onionland, a reference to the network's top level domain suffix .onion and the traffic anonymization technique of onion routing.

The dark web has often been confused with the deep web, the parts of the web not searched by search engines. This confusion dates to at least 2009. Since then, especially in reporting on Silk Road, the two terms have often been conflated, despite recommendations that they be distinguished.

Darknet websites are accessible only through networks such as Tor ("The Onion Router”) and I2P (“Invisible Internet Project”). Tor browser and Tor-accessible sites are widely used among the darknet users and can be identified by the domain “.onion”. While Tor focuses on providing anonymous access to the Internet, I2P specializes on allowing anonymous hosting of websites. Identities and locations of darknet users stay anonymous and cannot be tracked due to the layered encryption system. The darknet encryption technology routes users’ data through a large number of intermediate servers, which protects the users’ identity and guarantees anonymity. The transmitted information can be decrypted only by a subsequent node in the scheme, which leads to the exit node. The complicated system makes it almost impossible to reproduce the node path and decrypt the information layer by layer. Due to the high level of encryption, websites are not able to track geolocation and IP of their users as well as the users are not able to get this information about the host. Thus, communication between darknet users is highly encrypted allowing users to talk, blog, and share files confidentially.

...
Wikipedia