Tech Tip - Show File Extensions in File Explorer.
Ever since the introduction of Windows Vista, Windows appears to have been hiding file extensions. If you’re using Windows 10 and if you’d like to ensure that you can see the file extensions at a glance all of the time (and immediately be able to tell your .JPEGs from your .EXEs) follow these instructions...
1. Right mouse click on the Start button to open the Control Panel.
2. In the Control Panel open File Explorer Options (or Appearance and Personalization > File Explorer Options).
3. In the File Explorer Options window, click the "View" tab.
4. Uncheck the “Hide extensions for known file types” box.
5. Click OK.