Hide/exclude files?

Total newbie question:
I just started looking into Grav. To get the hang of it, I’d like to modify files and see what’s happening, e.g. default.md.

I’d like to keep the original file nearby, though. Easist would be to make a copy and just name it in a way that hides it from Grav. Is there a simple way to do just that?

A nice way of doing so would be prepending a ‘#’ to the filename, e.g. #default.md. That seem to work - at least sometimes. But is it the correct way?
Thanks, Dieter

Best thing is rename the original to .markdown - Grav will not pick it up, but it will still be recognizable as markdown file by you.