Very confused about a very simple thing about setting up hardware

[Xylem Flow]

I can't seem to find an answer to this probably because it's such a simple thing that it doesn't occur to anyone that it might need to be explained. But I'm not clear on something very simple.

 

So basically, I build a PC however I want, like I was going to use it as a desktop, and then install Unraid on it?

 

And I can use internal SATA HDDs vs USB HDDs?

[trurl]

Unraid is the operating system. You can host other operating systems as VMs on Unraid. Unraid storage needs to use SATA connections 

[Xylem Flow]

Great! Thank you. I thought that's how it would be, but I wasn't sure.