Sorry if this has been asked before, I haven't found anything about it here yet.
OK, this is my absolute beginner question:
I have access to multiple computers, all under Linux - not installed by me, but different variants (xUbuntu and others) and versions.
Where (in which folder) is hidden the valuable information about what variant and version of Linux is installed on any given computer?
Once I know which variant/version I'm dealing with, I will be able to ask more specific questions on this forum.