A `user.js` is a configuration file that can control hundreds of Firefox settings. For a more technical breakdown and explanation, you can read more on the [overview](https://github.com/ghacksuserjs/ghacks-user.js/wiki/1.1-Overview) wiki page.
The `ghacks user.js` is a **template** which aims to provide as much privacy and enhanced security as possible, and to reduce tracking and fingerprinting as much as possible - while minimizing any loss of functionality and breakage (but it will happen).
Everyone, experts included, should at least read the [implementation](https://github.com/ghacksuserjs/ghacks-user.js/wiki/1.3-Implementation) wiki page, as it contains important information regarding a few `ghacks user.js` settings.
Note that we do *not* recommend connecting over Tor on Firefox. Use the [Tor Browser](https://www.torproject.org/projects/torbrowser.html.en) if your [threat model](https://www.torproject.org/about/torusers.html.en) calls for it, or for accessing hidden services.
Also be aware that this `user.js` is made specifically for Firefox. Using it as-is in other Gecko-based browsers can be counterproductive, especially in the Tor Browser.
* The 12bytes article now uses this user.js and supplements it with an additional JS hosted at [GitLab](https://gitlab.com/labwrat/Firefox-user.js/tree/master)
<sup>1</sup> The ghacks user.js was an independent project by [Thorin-Oakenpants](https://github.com/Thorin-Oakenpants) started in early 2015 and was [first published](https://www.ghacks.net/2015/08/18/a-comprehensive-list-of-firefox-privacy-and-security-settings/) at ghacks in August 2015. With Martin Brinkmann's blessing, it will keep the ghacks name.
