The Dark Web is a term that refers specifically to a collection of websites that exist on an encrypted network and cannot be found by using traditional search engines or visited by using traditional browsers.
Almost all sites on the so-called Dark Web hide their identity using the Tor encryption tool. You may know Tor for its ability to hide your identity and activity.
You can use Tor to spoof your location so it appears you're in a different country to where you're really located, making it much like using a VPN service.
When a website is run through Tor it has much the same effect.
Indeed, it multiplies the effect. To visit a site on the Dark Web that is using Tor encryption, the web user needs to be using Tor. Just as the end user's IP address is bounced through several layers of encryption to appear to be at another IP address on the Tor network, so is that of the website.
There are several layers of magnitude more secrecy than the already secret act of using Tor to visit a website on the open internet - for both parties.
Thus, sites on the Dark Web can be visited by anyone, but it is very difficult to work out who is behind the sites. And it can be dangerous if you slip up and your identity is discovered.
You can also read our in-depth guide to using Tor if you want to know more about using the web anonymously and sending messages securely.