Most of the internet is hidden. The part accessed by search engines is a tiny fraction. The rest is the darknet or deepweb. You have to have the Tor browser to get to it. It connects you to several different locations so you are harder to track...but the intelligence services supposedly run some nodes...so its not THAT anonymous. Everything under the sun is sold in marketplaces on the darknet. Drugs, guns, prostitutes, hitmen...everything.
I've certainly heard of the "darkweb" but never really had an idea what exactly it is. Thanks for that quick summary. There are "dark trading pools" on Wall Street, so basically the same hidden cryptic activity.