It was built atop UNIX, the operating system originally created over 30 years ago by researchers at AT&T’s Bell Labs. … It was a better fit: Mac OS X shares conceptual roots with Linux, but it shares honest-to-goodness code with FreeBSD.

Is macOS based on UNIX or Linux?

macOS is a UNIX 03-compliant operating system certified by The Open Group. It has been since 2007, starting with MAC OS X 10.5. The only exception was Mac OS X 10.7 Lion, but compliance was regained with OS X 10.8 Mountain Lion.

Is Mac same as Linux?

macOS is a series of proprietary graphical operating systems which is provided by Apple Incorporation. It was earlier known as Mac OS X and later OS X. It is specifically designed for Apple mac computers. It is based on Unix operating system.
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Difference between Linux and macOS.