As the Surface Web, or WWW, is on the internet, the Dark Web exists on the Dark Net (or rather, multiple darknets).
It's important to point out that the terms Dark Web and Dark Net aren't the same thing. Dark Net was a term used in the 1970s', for networks that were isolated from ARPANET, mainly for security purposes, such as compartmentalization. They were configured to be able to receive external data, but they were hidden from the ARPANET network listings and wouldn't respond to networking inquiries, such as ping requests.
Over time, the term was also used for overlay networks, which are essentially networks that utilize software and hardware to create multiple layers of abstraction. These layers are run over multiple separate and discrete network layers on top, or over a common network (hence overlay), accessible only with special browsers or software, or where their IP addresses aren't globally routable. A few examples of such overlay networks are Tor, the Invisible internet Project (I2P), or FreeNet.
So, you can view the Dark Net as the infrastructure underneath the Dark Web, which is the content and websites that you can access only with the specialized software I mentioned, and which we will discuss as we proceed in this chapter, and in the book.
To give you an example of a Dark Net, I'll mention Tor, or The Onion Router. It's essentially a distributed network of servers or hosts, where users, traffic is bounced around between various routers.
This makes it hard to monitor the data, enhancing anonymity, privacy, and security.
The following diagram is from the Argonne National Laboratory website, and it demonstrates what I just mentioned in a graphical manner:
As you can see, the internet encompasses the Deep Web, which is in (or under) the Surface Web, and the Dark Web, which is on the Dark Net (yet another part of that magnificent network of networks known as the internet).
We will discuss who uses the Dark Web, and how, in this book, but let's take a high-level look first, before we dive in.