You cannot without erasing your hard drive and installing Mac OS 9 from scratch. Even then Mac OS 9 may not run on modern Mac hardware because Mac OS 9 needs the ROM chip to boot. Modern Mac OS X...
Macs are designed to function best with Mac OS X and the associated iLife software (iPhoto, iMovie etc.) but they can happily run Windows or Linux. Rather than change a Mac to the another operating...
The first version of Mac OS X appeared in 2001 and was numbered version 10.0 it had the name "Cheetah". Subsequent releases increased the point number and had a big cat name.
They were:10.1...