Alright, time to set some stuff straight:
Clearnet - normal websites that you browse day-to-day that can be accessed without any special care. This includes websites that don't have a domain name.
Deep Web - websites that do not show up on search engines, and thus are only accessible if someone sends you a link. This includes any clearnet website that either has no links to it or any website with a
robots.txt that stops webcrawlers from indexing them, and darknet websites.
Darknet - websites that require special software to resolve IP addresses or special DNS entries. When it comes down to it, all Tor, I2P, freenet, etc. are all just special flavors of software that allow you connect to other computers running that software. These systems also usually provide anonymity for the computers by trying to hide from anyone who may be listening in on the connection who the connection is to, and what the data being transmitted is.
LAN (Local Area Network) - The network of computers connected to a local router. Right now, you can download a webserver (like Apache or Nginx) and throw up a website with minimal issues. The first problem you will run into is that unless you're operating off of a business connection or have messed with your router configuration, it will appear that nobody can connect to it. Except somebody else at your physical location who is using your local IP address. This is because by default, routers (and sometimes ISPs) block the ports that webservers run on from being accessed through the internet. However, most routers will happily route connections through those same ports to local machines. Firewalls may not. Websites hosted here are considered part of the deep web but not the darknet, unless the webserver is also being hosted through Tor.
VPN (Virtual Private Network) - Basically, software that tricks your computer into thinking that it is connected to two local area networks -- the real one, and a fake one. The 'fake' one actually does route things over the network, but it tricks your computer and router into thinking it isn't. Basically everything about it is the same as LAN, it's just a LAN that actually works over the internet.
Local Storage - Harddrives, RAM, VRAM, CPU registers, etc. These are only accessible by your computer, and by no other computer.
Those are really the only "levels" of the internet. Even secret joint-taskforce classified SCIF data falls into these categories: they usually have a hardware terminal that has the information on local storage. Child research traffickers may elect to use any of the above, but probably primarily utilize VPN, darknet, and removable storage (local storage that can be removed from your computer with ease and plugged into another, usually usb drives but CD/DVD/Bluray/etc are not excluded). That goes for most other people perpetrating illegal activity too, since LAN isn't very useful (why not just talk to eachother?), the deep web could be ratted out by anyone and accessed by anyone, and the clearnet would be a very quick way to get picked up by your friendly neighborhood law enforcement division.
Some misconceptions on this very thread:
The deep web is websites you can't find on search engines, but you are probably thinking of the Dark web which are .onion sites that can only be accessed on Tor browsers.
This is mostly correct, but the "dark web" consists of much more than just .onion websites that can be accessed exclusively through Tor. There are lots of other darknet websites that operate through other networks rather than Tor.
this and u also need tails or whonix and a good vpn
You do not need tails or whonix (operating systems designed for anonymity that come with Tor installed, and have all connections at an OS level routed through them to prevent accidental leaks) or "a good vpn" to access the darknet. You may want to use them to improve anonymity.
edit: then theres the mariana's web but its possible that it doesnt even exist, and nobody has any idea at all how to access it
There is no "mariana's web." It doesn't even make sense. If nobody knew how to access it, then why would it exist? Maybe it can be considered an abstract idea of all the local area storage available to computers connected to the internet that can be accessed through hacking.. but that's kind of a long shot AND still falls into my categories above.
along with account settings pages on every site
This is a poor example of the dark web. There's technically no reason why a webcrawler couldn't or wouldn't identify this, it's just that usually you need to be logged in to access it, so if a webcrawler tries to access it they will just end up getting redirected to the login page.
technically speaking, your facebook page is on the deep web because a bot can't index it; it's dynamically created for you.
Also a poor example of the dark web. The darkweb refers to the concept of a page being unindexable, not the technicality that the page looks different for everyone that is logged in. For example, if you create a topic on the BLF right now, it is not the dark web simply because it has not yet been indexed by a webcrawler yet.
