Mac OS X 10.0.0 was the very first version of Mac OS X that was officially released to the public. This was the version of Mac OS X 10.0.0 "Cheetah" that appeared first on all original Mac OS X installation CDs. It, along with Mac OS X (10.0 itself), was officially released on March 24, 2001. * For key enhancements and new features, see the main articles Mac OS X or Mac OS X 10.0.