9. MS Windows 9 By Microsoft Windows 98, Win Xp, Win Vista, Win 7
10. 10 Most User Friendly MS Windows Wide range of applications By Microsoft Standard of game developed for pc. Windows 98, Win Xp, Win Vista, Win 7 Criticized heavily from security point of view.
12. Mac Os X 12 By Apple Cheetah, Tiger, Jaguar, Leopard
13. 13 Second most widely used OS Mac Os X Popular choice for designers By Apple Less targeted by security issues Cheetah, Tiger, Jaguar, Leopard Few hardware supported
15. Linux 15 By Linus Trovalds Includes ubuntu, debian, redhat, suse
16. 16 Most of the flavors are free Linux Large support for hardware and software By Linus Trovalds Popular OS for servers Includes ubuntu, debian, redhat, suse Can be difficult to operate