Tor Browser definition
The Tor Browser is a web broswer that anonymizes your web traffic using the Tor network, making it easy to protect your identity online.
If you're investigating a competitor, researching an opposing litigant in a legal dispute, or just think it's creepy for your ISP or the government to know what websites you visit, then the Tor Browser might be the right solution for you.
A few caveats: Browsing the web over Tor is slower than the clearnet, and some major web services block Tor users. Tor Browser is also illegal in authoritarian regimes that want to prevent citizens from reading, publishing, and communicating anonymously. Journalists and dissidents around the world have embraced Tor as a cornerstone of democracy online today, and researchers are hard at work improving Tor's anonymity properties.
Where to download Tor Browser
Tor Browser is available for Linux, Mac and Windows, and has also been ported to mobile. You can download desktop versions from the Tor Project website. If you're on Android, find OrBot or OrFox on the Google Play Store or F-Droid. iOS users can grab OnionBrowser from the Apple App Store.
How to use the Tor Browser
For most people, using Tor Browser is as simple as downloading it and running it, the same way you'd download Chrome or Firefox.
If you've never used Tor, the first thing you'll notice is that it's slow — or at least, slower than regular internet browsing. Still, Tor has gotten quite a bit faster over the years, and with a good internet connection, you can even watch YouTube videos over Tor.
Tor Browser gives you access to .onion web sites that are only available within the Tor network. For instance, try to access The New York Times at https://www.nytimes3xbfgragh.onion/ and Facebook at https://www.facebookcorewwwi.onion using a regular web browser. Go on. We'll still be here when you get back. Didn't work, did it? You can only reach these sites over Tor. This makes it possible to read the news anonymously, a desirable feature in a country where you don't want the government knowing which news sites you're reading, when you're reading them, and for how long.
Using Tor Browser comes with one major annoyance: Many prominent web services block access to Tor, often without useful error messages. If a site you normally visit suddenly returns 404 when visiting over Tor, the service is likely blocking Tor traffic and being needlessly opaque about it. Sites that do not block Tor might push you to click through a ton of captchas. It's not the end of the world, but it is annoying.
How Tor Browser works
Tor Browser routes all your web traffic through the Tor network, anonymizing it. As the images below illustrate, Tor consists of a three-layer proxy, like layers of an onion (hence Tor's onion logo). Tor Browser connects at random to one of the publicly listed entry nodes, bounces that traffic through a randomly selected middle relay, and finally spits out your traffic through the third and final exit node.
As a result, don't be surprised if Google or another service greets you in a foreign tongue. These services look at your IP address and guesstimate your country and language, but when using Tor, you will often appear to be in a physical location halfway around the world.
If you live in a regime that blocks Tor or need to access a web service that blocks Tor, you can also configure Tor Browser to use bridges. Unlike Tor's entry and exit nodes, bridge IP addresses are not publicly listed, making it difficult for web services, or governments, to blacklist those IP addresses.
The Tor network routes TCP traffic of all kinds but is optimized for web browsing. Tor does not support UDP, so don't try to torrent free software ISOs, as it won't work.
Is Tor Browser legal?
For most people reading this article, Tor Browser is completely legal to use. In some countries, however, Tor is either illegal or blocked by national authorities. China has outlawed the anonymity service and blocks Tor traffic from crossing the Great Firewall. Countries such as Russia, Saudi Arabia and Iran, are working hard to prevent citizens from using Tor. Most recently, Venezuela has blocked all Tor traffic.
It's easy to see why a repressive regime hates Tor. The service makes it easy for journalists to report on corruption and helps dissidents organize against political repression.
The freedom to communicate, publish, and read anonymously is a prerequisite for freedom of expression online, and thus a prerequisite for democracy today. Using and supporting Tor helps support freedom of expression around the world. Technically sophisticated users are encouraged to donate bandwidth to the Tor network by running a relay.
How to get on the dark web?
Let's get this "dark web" nonsense out of the way once and for all. While it's true that some criminals use Tor to commit crimes, criminals also use the regular internet to commit crimes. Bank robbers use getaway cars on public highways to commit crimes. We don't slander highways or the internet, because that would be foolish. Tor has tons of legitimate uses and is considered by many a cornerstone of democracy today.
So when you hear people talking in scared whispers about the “dark web” or the “deep web” or somesuch nonsense, understand that there is a lot more going on here than just "The Four Horsemen of the Infocalypse are using computers in non-normative ways." Anonymity online is not merely the bailiwick of criminals and trolls.
As a practical matter, Tor is for ordinary people, because criminals willing to break the law can achieve better anonymity than Tor provides. As the Tor FAQ points out:
Doesn't Tor enable criminals to do bad things?
Criminals can already do bad things. Since they're willing to break laws, they already have lots of options available that provide better privacy than Tor provides. They can steal cell phones, use them, and throw them in a ditch; they can crack into computers in Korea or Brazil and use them to launch abusive activities; they can use spyware, viruses, and other techniques to take control of literally millions of Windows machines around the world.
Tor aims to provide protection for ordinary people who want to follow the law. Only criminals have privacy right now, and we need to fix that.
Is Tor Browser anonymous?
Tor Browser offers the best anonymous web browsing available today, but that anonymity is not perfect. We are currently witnessing an arms race between researchers seeking to strengthen Tor, or even develop a next generation anonymity tool, and governments around the world studying how to break Tor's anonymity properties.
The most successful technique to de-anonymize Tor Browser users has been to hack them. The FBI has used this technique successfully in numerous criminal cases, and under Rule 41, enacted in 2016 by US Chief Justice Roberts of the Supreme Court, the FBI can now mass hack large numbers of computers anywhere in the world using a single warrant.
Such hacking techniques ought to concern everyone, as innocent Tor users will inevitably get caught up in such fishing expeditions.
Does that mean you shouldn't use Tor? Certainly not, if you care about your privacy online. Tor Browser is an essential tool that will only improve with time. If you don't care about your privacy? Well, Edward Snowden said it best:
Arguing that you don't care about the right to privacy because you have nothing to hide is no different than saying you don't care about free speech because you have nothing to say.