I have long considered writing a post about the un-indexed web and the deep web (that can be accessed through tor). Whenever I started writing the post, something in my mind was telling me "STOP". That is because of the dark stigma related to the deepweb. I will start explaining exactly what these hidden internets are with an analogy.
Imagine the normal internet as being Boston. You live far away from New York City and are sometimes influenced by it, however, without prior knowledge you do not know that it is there. Boston is big, but further out there is a much larger city waiting to be discovered. You hop a ride on a special device called a car (a tor analogy) and ride into the large city, amazed at it's size. That is what this masked internet is like.
There is a difference between the unindexed internet and what people refer to as the "deep web". The unindexed internet is simply not cataloged by search engines due to being under password protection. For a safe example of what the unindexed web is like, go to www.strange.com. It is illegal to break into the servers, so what information is hidden is not legally accessible.
The "deepweb", on the other hand, is perfectly legal to view despite it housing content that is illegal in most countries. To access this internet, I would recommend downloading the tor browser bundle from www.torproject.org. You need some version of tor, but the browser bundle contains everything someone new to using it will need to keep safe. In addition to using tor setting up a proxy may be a good move to further protect yourself.
WARNING: Before you go any further make sure that you have cleared your internet history in all of your browsers and closed all processes relating to them.
ANOTHER WARNING: Some of the content located in the deep web is illegal to view. You can legally visit the deep web as long as you do not seek out this content.
Once you have the tor browser bundle, have closed all necessary processes, have a proxy set up to work with tor (optional), you are prepared to take your first step into the deep web. Start off with a popular starting point: kpvz7ki2v5agwt35.onion
As you can see that address has a new extension and an odd location. Copy and paste it into your tor browser as-is. Tor is slow, so be patient while you wait for it to load. A white screen should pop up with a link to the hidden wiki. The hidden wiki is a collection of links to useful services, like search engines for the deep web, email services, forums, hosting services, etc. I have never actually traveled beyond the articles on the hidden wiki since I do not want to stumble upon anything that could give me a criminal record or attempt to infect my computer with a virus (which I have no worries for, since I am a Linux user, but for those Windows users out there, I warned you.)
Here are some neat facts about the masked internets
The hidden internets make up about 99% of all of the interenet. The surface web with sites like facebook, twitter, google, etc. make up only a small 1%.
Much of that content is raw information that is poorly organized, but searchable.
A hidden operating system used to be available for download. The broken link still remains on the hidden wiki.
Several operating systems are dedicated to private browsing and/or the deep web, using default settings that protect your privacy even further than a normal OS.
So I have taught AND warned you about this internet. What you do with the information is your choice. I have never been any further than the hidden wiki, but just from some of the links that I have read there I can see that some of the content is dangerous (assassin markets and drug trade, just to name a few). So if you just wish to stick your head it like me, I wouldn't venture any further out than the hidden wiki.