Linux is the kernel... so shouldn't the question be "What's the most popular operating system distribution built on a linux kernel?" Even at that point you hav

Linux is the kernel... so shouldn't the question be "What's the most popular operating system distribution built on a linux kernel?" Even at that point you have to specify whether Ubuntu and it's progeny are all considered Debian distros or their own thing; if the former, then is Debian its own thing or a development of SLS?