About url in firefox

There are few special URLs which begins with about: that you can type into the firefox location bar:

about: => The same page as Help -> About
about:blank => A blank page
about:cache => Displays cache statistics and directory location
about:config => GUI for modifying user preferences
about:plugins => List all plugins
about:logo => Displays the firefox logo

There is an extension available for firefox to save advanced preferences. gui:config makes it easier to change preferences that can only be found in the “about:config”. This add on can be downloaded from https://addons.mozilla.org/en-US/firefox/addon/5523