Files extension is hidden in Windows by default. You can unhide it by: Open Control Panel > Appearance and Personalization.   Click on Folder Options or File Explorer Option. Click the View tab, under Advanced Settings, you will see the option Hide extensions for known file types. Uncheck this option and click on Apply and OK. Windows 10 users may also search for File Explorer Options in the Start search box and open this box. For more details, refer to https://www.thewindowsclub.com/show-file-extensions-in-windows