Generally speaking, we don't recommend using a VPN with Tor unless you're an advanced user who knows how to configure both in a way that doesn't compromise your privacy.
You can find more detailed information about Tor + VPN at our wiki.
Tor Browser is currently available on Windows, Linux and macOS.
There is a version of Tor Browser for Android and The Guardian Project also provides the app Orbot to route other apps on your Android device over the Tor network.
There is no official version of Tor for iOS yet, though we recommend Onion Browser.
It's strongly discouraged to install new add-ons in Tor Browser, because they can compromise your privacy and security.
Installing new add-ons may affect Tor Browser in unforeseen ways and potentially make your Tor Browser fingerprint unique.
If your copy of Tor Browser has a unique fingerprint, your browsing activities can be deanonymized and tracked even though you are using Tor Browser.
Basically, each browser's settings and features create what is called a "browser fingerprint".
Most browsers inadvertently create a unique fingerprint for each user which can be tracked across the internet.
Tor Browser is specifically engineered to have a nearly identical (we're not perfect!) fingerprint across it's users.
This means each Tor Browser user looks like every other Tor Browser user, making it difficult to track any individual user.
There's also a good chance a new add-on will increase the attack surface of Tor Browser.
This may allow sensitive data to be leaked or allow an attacker to infect Tor Browser.
The add-on itself could even be maliciously designed to spy on you.
Tor Browser already comes installed with two add-ons — HTTPS Everywhere and NoScript — and adding anything else could deanonymize you.
Want to learn more about browser fingerprinting? Here's an article on The Tor Blog all about it!
Tor Browser can certainly help people access your website in places where it is blocked.
Most of the time, simply downloading the Tor Browser and then using it to navigate to the blocked site will allow access.
In places where there is heavy censorship we have a number of censorship circumvention options available, including pluggable transports.
For more information, please see the Tor Browser User Manual section on censorship.
Tor Browser prevents people from knowing the websites you visit.
Some entities, such as your Internet Service Provider (ISP), may be able to see that you're using Tor, but they won't know where you're going when you do.