Windows 7 system how to show or hide File extensions?

Solution:

File extension is added at the end of the file name of a set of characters that is used to determine if you should open the file. Follow the steps below to select the Windows display those file extensions.

1. Click Windows "Start" - "Control Panel" - "Appearance and Personalization", and then click the "Folder Options".

2. Click the "View" tab, and then in the "Advanced settings" under implemented one of the following:

To hide the file extensions, select the "Hide extensions for known file types" check box, and then click OK.

To show file name extensions, clear the "Hide extensions for known file types" check box, and then click OK.