This extension shows whether the application is running with Windows administrator privileges, by means of a little icon in the status bar. This is useful if you're logged in as an administrator by default and you use privilege limitation tools such as MSDN DropMyRights, Run As or Windows' User Account Control (Windows Vista and newer). Now you can see at a glance whether these tools are activated.
Starting with Firefox 29 or IsAdmin 2.5, the IsAdmin button can also be placed on the navigation toolbar instead of the add-on bar.
This add-on will become unavailable once Mozilla drops support for XUL add-ons. It will not be possible to port this add-on to the restrictive WebExtensions system. Why not try the Pale Moon browser instead? It supports this add-on and many more.