It's often important to know what version of Firefox you are using, to help you troubleshoot a problem or just to know if Firefox is up to date. Here is how you can find out.
Click the menu button 
, click and select .On the menu bar, click the menu and select . The About Firefox window will appear. The version number is listed underneath the Firefox name.
Here is an example of what the About Firefox window will look like:
Opening the About Firefox window will, by default, start an update check. If an updated version of Firefox is available, it will be automatically downloaded. On Linux, this will happen only if you use a build downloaded from Mozilla's website; otherwise, updates will come through your Package Manager. For more information, see Update Firefox to the latest release.
