Based on FreeBSD and Mach kernel (also derived from BSD). NeXTSTEP OS for Next computer started by Steve Jobs after being pushed out of Apple, was based on FreeBSD and Mach. When Jobs returned to Apple, the original macOS was replaced by a derivative of the NeXTSTEP operating system.

MacOS is the most popular Unix platform by far among individual computer users. More than 100 million Macs in use today. Server market share is quite different.

MacOS allows users to run Unix-based open source software alongside commercial products like MS Office, without the use of VMs.