“A while back, someone asked me why the open-source BSD
operating systems aren’t as popular as Linux. It’s a good question.
Technically speaking, the BSDs are often every bit as good as
Linux. Indeed, when it comes to security, OpenBSD is the best of
breed.“Indeed, you can argue that BSD is actually more successful than
Linux on the desktop. I’m referring, of course, to MacOS X, which
is based on Darwin. Darwin, in turn, is built on top of Mach 3.0
operating-system services, which runs on top of the 4.4 BSD
operating system.“However, developers usually see Darwin simply as the foundation
for MacOS X and its Cocoa and Carbon toolkit-based application.
Apple says it would like Darwin to become an operating system in
its own right for both its native PowerPC and Intel’s
architectures. In practice, though, Darwin has made little progress
as an independent operating system…”