Torbutton is a 1-click way to enable or disable the use of Tor. It adds a
panel to the statusbar that says "Tor Enabled" (in green) or "Tor Disabled"
(in red). The user may click on the panel to toggle the status. If the user
(or some other extension) changes the proxy settings, the change is
automatically reflected in the statusbar.

Some users may prefer a toolbar button instead of a statusbar panel. Such a
button is included, and one adds it to the toolbar by right-clicking on the
desired toolbar, selecting "Customize...", and then dragging the Torbutton
icon onto the toolbar. There is an option in the preferences to hide the
statusbar panel (Tools->Extensions, select Torbutton, and click on
Preferences).

Newer Firefox versions have the ability to send DNS resolves through the
socks proxy, and Torbutton will make use of this feature if it is
available.

WWW: http://torbutton.torproject.org/dev/