Why doesn't Koala see scss files that start with _?

Question

Sass

I'm slowly starting to learn SASS technology and ran into the following problem. I have ready-made scss files from the Bootstrap framework in my project folder. The names of all its files begin with an underscore _ . When I create a new project in Koala and specify a folder with Bootstrap files, the compiler does not see them, but if I remove the underline, then everything is fine.
Question: Is it supposed to be like this? Or is it some kind of glitch

Answer 1

Because such specifics of sass.
First, read about sass ...
Learn:
sass-lang.com/guide
See the Import section