The dark web is a small subset of the deep web, which is part of the internet that is not found using search engines. That includes many websites that require users to log in with an username and password, and the deep web is estimated to be about 400 to 500 times larger than the common internet. The dark web is relatively smaller — it is made up of a series of encrypted networks that is able to hide users' identities and locations and can only be accessed with special software.
The most popular of those networks is called TOR, or The Onion Router, which was developed initially for government use before it was made available to the general public.
"When people typically refer to the dark web, a lot of the time they're referring to a portion of the internet that's accessible using an anonymous browsing network called TOR," Charles Carmakal, a vice president at cybersecurity firm FireEye, told CNBC's "Beyond the Valley" podcast.
One of the primary functions of the TOR network is that it allows users to access ".onion" pages, which are specially encrypted for maximum privacy.
Carmakal explained that TOR also lets users connect to normal websites anonymously so that their internet service providers cannot tell what they're browsing. Similarly, the websites will not be able to pinpoint the location of the users browsing their pages.
On the TOR browser, the connection requests are re-routed several times before reaching their destination. For example, if a user in Singapore is trying to connect to a website in London, that request on a TOR browser could be routed from Singapore to New York to Sydney to Capetown to, finally, London.