Naked Security
You probably don’t need to be told what sort of products were on offer at an online retail site called DarkMarket.
As you can imagine, it operated on the so-called dark web, and you’d have needed the Tor browser to access it, using a special web address ending in .onion.
Onion addresses can only be reached via Tor – you don’t, and indeed can’t, look up the IP number where they can be reached on the internet, as you can with regular sites like nakedsecurity.sophos.com (192.0.66.200 at the time of writing, if you were wondering).
Instead, you need to connect to the Tor network and ask it to locate and connect to onion sites for you, assuming you know what onion address to use in the first place.
Using a special anonymising protocol, Tor arranges for the “other end” of your anonymised connection into Tor to be paired up with the “other end” of the relevant onion site’s connection into Tor, after which you can talk to each other.
Your traffic gets all the way to the onion site, but you have no idea where that site is because you can only trace your packets until they first enter the Tor network.
Similarly, the server’s replies get back to you, but the server has no idea where you are, for the same reason in reverse.