[danans]

For a historical perspective ... way back in the day there was Unix at Bell Labs, and one of it's licensed derivatives was made by Berkeley Systems, and hence their distribution was called BSD.

Unix split into 2 main variants, BSD and System 5 Unix. Most commercial derivations were based on System 5, and BSD was used in academia.

A short time later Linus created his own System 5 Unix-inspired OS kernel, Linux, but from clean cloth, and distributed it with userspace tools borrowed from yet another OS project called GNU created by Richard Stallman.

The various BSDs (FreeBSD, OpenBSD, Darwin, etc) are descendants of the original BSD.

People used to say BSD and it's children were "real" Unix and Linux was not, though I don't think many care about that anymore.