This is a reference to the entries in about:config, where all user preferences can be viewed and modified. In most cases the list below doesn't state whether a given preference applies to all, or only some (and which), of Firefox, Thunderbird, Mozilla Suite, SeaMonkey, or even the now discontinued Sunbird: trial and error is often the only way to tell if some particular preference applies to your version of your application.

This article does not contain a complete list of all preferences.