Tor Browser, previously known as Tor Browser Bundle, is a web browser that protects your privacy while you are surfing the Internet. It's a modified version of Mozilla Firefox ESR (Extended Support Release) that includes TorButton, TorLauncher, NoScript and HTTPS Everywhere Firefox extensions, and the Tor proxy.
Tor Browser automatically starts the Tor background processes and routes traffic through the Tor network; sensitive data like cookies and the browsing history are removed upon closing the browser.
Its main purpose is to circumvent censorship by concealing its users' identities and their online activity from surveillance and traffic analysis. This is done by using using thousands of servers (Tor relays), multi-layered encryption, isolating each website you visit so third-party trackers can't follow you, prevent someone watching your connection from knowing what websites you visit, and make it difficult to be fingerprinted based on your device and browser info.
Use it to access sites that may be blocked in your country or region, or to prevent somebody watching your Internet connection from learning what sites you visit, but do keep in mind that nothing is foolproof! Anyone monitoring your browsing habits can still see that you're using Tor, so keep that in mind before using it.
This article explains installing Tor Browser on Linux, providing 3 options (2 of them using Tor Browser Launcher, see below for details) for this.
Do not confuse Tor Browser with the Tor client. If you want to use Tor with other applications, check out: How To Install And Use Tor (Client) As A Proxy In Ubuntu Or Linux Mint.