Firefox makes use of special URL commands to display its internal pages for configuration and functionality. For example, about:blank command in the address bar displays a blank page and about:config displays all the Firefox configuration.
Normally we don’t use most of the functionality offered by About: commands in Firefox but some times these commands come in very handy to tweak the browser functionality according to our needs or troubleshooting the browser malfunctioning.
Here is the complete list of Firefox About: commands along with their short descriptions
Using the About: commands in Firefox is quite simple. You just have to enter the command in the Firefox address bar and press enter. This is like entering the URL of any webpage to open it. For example, if I want to know more about my installed version of Firefox, I will write about: in the Firefox address bar. Pressing enter will bring me the information I want.
Just for Fun
about:mozilla Shows a verse from the book of Mozilla
about:robots A robot greets the humans
Shows information about Firefox like version, contributors, build configuration etc.
Shows the error page when the browser is not able to access the requested page
Shows the permissions page where you can see the permissions given by the user for each visited website including password storage information, location sharing, pop-ups allowance, offline storage etc
Shows vital stats about Firefox performance
Shows the information about performance, hardware, usage and customizations collected by Telemetry. This information is submitted to Mozilla to help improve Mozilla Firefox. Telemetry is disabled by default. You can enable it from this page
Which About: command do you use the most? Did I miss any command? Please share your thoughts by clicking here.