The Tor software is the currently best Internet privacy tool available. It should be downloaded from https://www.torproject.org/ if this site is available. This site is not available in many countries.
Users who do not have access to the official Tor website due to censorship can in many cases download the source code directly from git. This can be done with the following command:
git clone git://git.torproject.org/git/tor
The code can later be updated by running git pull in the Tor directory.
You can also get the Tor software by sending an e-mail with the subject allahu akbar to email@example.com.
Always make sure you verify the GnuPG signature of Tor and Tor related binaries before installing.