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/arkenfox/user.js/wiki/1.1-Overview) wiki page.
The `arkenfox 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/arkenfox/user.js/wiki/1.3-Implementation) wiki page, as it contains important information regarding a few `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 the `arkenfox user.js` is made specifically for desktop Firefox. Using it as-is in other Gecko-based browsers can be counterproductive, especially in the Tor Browser.
* This [12bytes article](https://12bytes.org/articles/tech/firefox/firefoxgecko-configuration-guide-for-privacy-and-performance-buffs) which uses the `arkenfox user.js` and supplements it with an additional JS hosted at [Codeberg](https://codeberg.org/12bytes.org/Firefox-user.js-supplement)
