In it’s broadest sense, the Deep Web is simply any part of the Internet not indexed by search engines. This includes anything that requires an account to access, such as webmail, online banking, subscription services etc. However what is meant most often when someone talks about the Deep Web is the parts of the Internet which cannot be accessed through a normal web browser — the more specific term for this is the Dark Web.
There are many networks which constitute the Dark Web, however the most well-known and among the largest is TOR network. TOR was developed by the U.S.. Navy during the 90s to secure intelligence communications for the U.S.. government. TOR software has since been released to the public, and is now used for circumventing censorship, whistleblowing, evasion of cyberstalkers, and most infamously, illegal trade.
The acronym “TOR” stands for “The Onion Router” and refers to the protocol used to transmit data. Each node on the TOR network decrypts one layer of a transmission, to learn where to send it next. The next node receiving the transmission does not know whether it is coming from the original sender or just another node, making it very difficult to trace back a transmission back to its original sender. The last node the transmission is sent to is an “exit node”, which decrypts the transmission itself and delivers it to the receiver. It is important to note that the exit node can see the contents of the transmission, although it does not know who the original sender is. Therefore it is highly recommended to use end-to-end encryption for any communication via TOR. Fortunately the browser bundled with TOR helps with this, with features such as HTTPS-everywhere being enabled by default.
The TOR software bundle can be downloaded from the official TOR project website: https://www.torproject.org/download/download.html.en
Before using TOR, be sure to read the recommendations listed by the TOR project: https://www.torproject.org/download/download.html.en#warning
Once you have downloaded TOR, what are you going to do with it? It is possible to visit any regular, surface website with TOR, and your transmissions will be sent over the TOR network to protect your privacy. More than likely however you have downloaded TOR to visit sites not accessible on the surface web. If this is the case, below are a few “.onion” sites to start you off. These are only accessible via TOR:
Hidden Wiki (contains links to all kinds of TOR hidden services) – http://zqktlwi4fecvo6ri.onion/wiki/index.php/Main_Page
AHMIA (search engine which indexes .onion sites) http://msydqstlz2kzerdg.onion/
TorLinks (similar to Hidden Wiki) – http://torlinksd6pdnihy.onion/
Torch (another .onion search engine) – http://xmh57jrzrnw6insl.onion/a
Browsing websites (be they surface sites or .onion) via TOR has a number of tradeoffs. The onion routing protocol slows everything down, so browsing will be much slower than normal. Some websites will not allow you to post content or even visit the site when using TOR, because the exit node you are using to connect has been blocked (normally due to abuse in the past). In addition, you will not be able to use most browser extensions or plugins such as Flash. While you can add them, doing so can compromise privacy which defeats the purpose of using TOR in the first place.