The Onion Router, better known as “Tor”, is designed to allow a user to browse the Internet anonymously via a volunteer network of more than 5000 relays. It doesn’t share your identifying information like your IP address and location with websites or service providers. There are arguably legitimate uses for this technology, such as providing Internet access in repressively regulated countries. Most admins will want to prohibit their users from using the Tor network due to its association with nefarious activity. It is also known as DeepNet or Deep Web.
Source: https://thehackernews.com/2015/03/tor-how-to-protect.html