Beyond the Internet content that many can easily access online lies another layer—indeed a much larger layer—of material that is not accessed through a traditional online search. The furthest corners of the Deep Web, known as the Dark Web, contain content that has been intentionally concealed. The Dark Web may be accessed both for legitimate purposes and to conceal criminal or otherwise malicious activities. It is the exploitation of the Dark Web for illegal practices that has garnered the interest of officials and policy makers. It is unclear, however, how much of the Deep Web is taken up by Dark Web content and how much of the Dark Web is used for legal or illegal activities. Users route their web traffic through other users' computers such that the traffic cannot be traced to the original user. Users often navigate Dark Web sites through directories such as the "Hidden Wiki," which organizes sites by category, similar to Wikipedia. In addition to the wikis, individuals can also search the Dark Web with search engines. These search engines may be broad, searching across the Deep Web, or they may be more specific. Other developers have created tools—such as Tor2web—that may allow individuals access to Tor-hosted content without downloading and installing the Tor software. While tools such as Tor aim to anonymize content and activity, researchers and security experts are constantly developing means by which certain hidden services or individuals could be identified or "deanonymized." Anonymizing services have been used for legal and illegal activities ranging from keeping sensitive communications private to selling illegal drugs. Illegal Activity and the Dark Web

Just as nefarious activity can occur through the Surface Web, it can also occur on the Deep Web and Dark Web. A range of malicious actors leverage cyberspace, from criminals to terrorists to state-sponsored spies. The web can serve as a forum for conversation, coordination, and action. The actual percentage of these that serve a particular illicit market at any one time is unclear, and it is even less clear how much Tor traffic is going to any given site. Government Use of the Dark Web

Because of the anonymity provided by Tor and other software such as I2P, the Dark Web can be a playground for nefarious actors online. Law Enforcement

Just as criminals can leverage the anonymity of the Dark Web, so too can law enforcement. It may use this to conduct online surveillance and sting operations and to maintain anonymous tip lines. Military and Intelligence

Anonymity in the Dark Web can be used to shield military command and control systems in the field from identification and hacking by adversaries. Tor software can be used by the military to conduct a clandestine or covert computer network operation such as taking down a website or a denial of service attack, or to intercept and inhibit enemy communications. Individuals, businesses, and governments may all rely upon the digital underground.
The layers of the Internet go far beyond the surface content that many can easily access in their daily searches. The other content is that of the Deep Web, content that has not been indexed by traditional search engines such as Google. The furthest corners of the Deep Web, segments known as the Dark Web, contain content that has been intentionally concealed. The Dark Web may be used for legitimate purposes as well as to conceal criminal or otherwise malicious activities. It is the exploitation of the Dark Web for illegal practices that has garnered the interest of officials and policy makers.
Individuals can access the Dark Web by using special software such as Tor (short for The Onion Router). Tor relies upon a network of volunteer computers to route users' web traffic through a series of other users' computers such that the traffic cannot be traced to the original user. Some developers have created tools—such as Tor2web—that may allow individuals access to Tor-hosted content without downloading and installing the Tor software, though accessing the Dark Web through these means does not anonymize activity. Once on the Dark Web, users often navigate it through directories such as the "Hidden Wiki," which organizes sites by category, similar to Wikipedia. Individuals can also search the Dark Web with search engines, which may be broad, searching across the Deep Web, or more specific, searching for contraband like illicit drugs, guns, or counterfeit money. While on the Dark Web, individuals may communicate through means such as secure email, web chats, or personal messaging hosted on Tor. Though tools such as Tor aim to anonymize content and activity, researchers and security experts are constantly developing means by which certain hidden services or individuals could be identified or "deanonymized."
Anonymizing services such as Tor have been used for legal and illegal activities ranging from maintaining privacy to selling illegal goods—mainly purchased with Bitcoin or other digital currencies. They may be used to circumvent censorship, access blocked content, or maintain the privacy of sensitive communications or business plans. However, a range of malicious actors, from criminals to terrorists to state-sponsored spies, can also leverage cyberspace and the Dark Web can serve as a forum for conversation, coordination, and action. It is unclear how much of the Dark Web is dedicated to serving a particular illicit market at any one time, and, because of the anonymity of services such as Tor, it is even further unclear how much traffic is actually flowing to any given site.
Just as criminals can rely upon the anonymity of the Dark Web, so too can the law enforcement, military, and intelligence communities. They may, for example, use it to conduct online surveillance and sting operations and to maintain anonymous tip lines. Anonymity in the Dark Web can be used to shield officials from identification and hacking by adversaries. It can also be used to conduct a clandestine or covert computer network operation such as taking down a website or a denial of service attack, or to intercept communications. Reportedly, officials are continuously working on expanding techniques to deanonymize activity on the Dark Web and identify malicious actors online.