Showing file extension on Project tab

Hello, I am unity beginner and having trouble showing file extension of Project tab. I am studying with books I bought and their pictures have extensions like “player.prefeb” while mine shows “player” only. Is there anyway to show file extension on unity?
Thank you

You can see the file extension at the bottom of the Project tab when you select the file (resize if it’s cutoff).

If you can’t see an extension when selecting the file, then you probably have the Project window in ‘one column layout’, so just change it to ‘two column layout’.

Hope this helps

But I want to work with one column T^T
Thanks by the way.

PROGrand/FileExtensions.cs is the solution.