Tor Browser is a built on the Firefox Internet browser, but it is built-in the Tor software, so it is a VPN which aims to stay anonymous while browsing the Internet and it changes the IP address and skip the blocked sites, it lets access the deep web and so on ...
Open the terminal Ctrl + Alt + T and paste the following commands :
sudo add-apt-repository ppa:upubuntu-com/tor-bundle
sudo apt-get update
sudo apt-get install tor-browser