Tor Browser (TB) is a customized version of Firefox Extended Service
Release built specifically for internet browsing over the Tor
anonymity network.

TB's configuration aims to mitigate attacks on a client's anonymity,
including determining the client's actual IP address and browser
fingerprinting.  Other aspects of Firefox have also been patched
to plug privacy leaks in ways not possible any other way.

You are recommended to read about TB and privacy from tor-project documentation.

Remember that there are no perfect privacy or anonymity solutions, and
this includes TB.  As always you must pay attention and in many cases
modify your behavior to ensure your privacy online.