Setting up multiple Firefox profiles
A browser love story
Reasons to have multiple profiles
For the casual user, you may want to have different profiles for different family members. This would allow each person to have their own set of bookmarks, settings, and add-ons, and not have them be all mixed together in one.
For web developers, you may want to be able to test your website, web app, or project on different Firefox channels, without mixing up your primary profile.
Available browser development channels
There are four available browser channels, each at a different level of stability and development. The four channels are Stable, Beta, Aurora, and Nightly. Most users are going to want to use the Stable channel as it is the most end-user ready. However, for those more adventurous, you can try one of the other three channels to see what is coming in Firefox and play around with emerging features. As you go up, each channel risks being more unstable than the previous, with Nightly being the most unstable.