Online activity is an important area for parents to protect their teens from potential harm. But even the most Internet savvy parents may not realize that there is an area of the Internet that can expose their teens to serious danger.

There are basically three parts to the world wide web: the surface web, deep web, and dark web.

The surface web is everything that’s publicly available and accessible through search engines or typing a URL into your browser. It’s the common Internet everyone uses to read articles, find news, peruse social media, and shop online.

The deep web is all the content on the web that is not indexed by standard search engines, such as email clients, online banking websites, and secured networks (schools, governments, companies, etc.). Some of those pages can still be accessed if you have the exact URL, while other pages require you to have login credentials.

The dark web is a small portion of the deep web, though sometimes people confuse the two terms. The dark web’s main function is to provide anonymity to users, which attracts people who are concerned about privacy. Unfortunately, that means it also attracts users who want to offer illegal products or services. You can buy credit card numbers, all manner of drugs, guns, counterfeit money, stolen subscription credentials, hacked Netflix accounts and software that helps you break into other people’s computers. The dark web is also filled with disturbing photos and videos, such as videos of child pornography, murders, and rape.

To gain access to the dark web, individuals must use special proxying software or browsers (TOR is the most common one used). Sadly, there are plenty of sites on the surface web that provide a step-by-step guide on how to gain access to the dark web. It is very easy for a teen to obtain one of these guides and begin exploring the dark web. Additionally, everything done on the dark web is anonymous and leaves nothing stored on their device for you to find.

Although the dark web is a real problem, there is a positive use for it: journalists and activists also use the dark web to avoid being traced by autocratic governments, and a service like TOR is a useful tool for many users to bypass state censorship and crackdowns on the internet. That said, there is not a legitimate reason for your American teen to be on it, so please get involved if you hear your teen discussing TOR or the dark web.