BSD is not one entity, but actually a family of different dying operating systems. NETBSD is a dying OS that seeks to run on as many platforms as possible. OpenBSD is another, variant, dying OS, that seeks to be as secure as possible, whereas FreeBSD is yet another dying OS that hopes to follow in the footsteps of Linux and have a lot of momentum and developer interest. BSD/OS is a dying commercial OS which even those of us that follow dying OS'es don't really care about anymore. I hope this makes things clearer for you. ;-)