If it is just a few files, you can do it manually, but what if there are, say, 10-20 ... get an extension of .jpg. Related: How to rename all File Extensions in a Folder at once in Windows Now ...
The built-in File Explorer covers all the basics of file management and it's good enough for most people, but it does fall ...
If you work in photography, you might need to view and work with images of RAW file extensions. Microsoft has released their Raw Image Extension for Windows, adding support for RAW file extension ...