Imagine the most messed up thing you've ever found online. Now think of the sketchy corner of the internet where you found it.
Think of that as the proverbial iceberg. The tip of it above the water is the "regular" web, whatever you can see with a Google search, no matter how far into the results you go.
Then underneath the water, there's everything else - a huge mass of secret web sites that the search engines don't even see. Welcome to the deep web.
Not everything down here is shady. The deep web includes things like private web sites for a company's employees, or for governments.
The point of the deep web is that it's anonymous. That's what makes it secure for those kinds of purposes. Here's where you can communicate — hopefully — without the snooping eyes of the nsa.
But it's also what makes it secure for criminals, black hat (or unethical) hackers, or anyone else who needs to get something done online without leaving a trace. The deep web is where you can buy drugs, trade illegal porn, and, as web legend has it, even hire a hitman.
The various sites where you can do so can only be reached by programs that mask your ip address.
Online, the flow of information is free, and the deep web really can't be stopped.
Arielle Castillo is Fusion's culture editor, reporting on arts, music, culture, and subcultures from the streets on up. She's also a connoisseur of weird Florida, weightlifting, and cats.