A good list of popular Operating Systems are listed here (taken from "www.bellevuelinux.org"): AIX
Amiga BeOS
Darwin
FreeBSD
FreeDOS
GNU/Hurd
HP-UX IRIX
JavaOS
Linux
Mac OS X
Microsoft Windows MINIX
MS-DOS NetBSD
OpenBSD
Palm OS
QNX
SkyOS
Solaris
TRON Tru64
An operating system is the main software that runs a computer, without an operating system a computer is almost useless.
There is no best operating system, they all have their advantages/disadvantages and were all developed with some kind of goal in mind.
1: All the company's servers used Unix (OS), but now they use Linux (OS).
2: George had a quadruple boot with multiple OSs running on his PC, it ran Microsoft Windows Vista Ultimate, Mac OS X Leopard, and two flavors of Linux.
Operating system. Simply, a program that runs your computer. Examples of an operating system are CP/M, DOS, Windows, Mac OS, Linux, and Palm OS, though there are many more. One will oftentimes become overly attached to their OS, preaching it as though it were a religion and shunning all who use anything even slightly different.
Man: My OS of choice is Windows XP.
Woman: My OS of choice is Mac OS X.
Man & Woman: (killing eachother)
Supa-Nerd: My OS of choice is CP/M! 8086 FOREVAH!!!
oS stands for Old School. 'Tis an abbreviation for oS.
The lowercase-then-uppercase type is a way of making it look cooler. "oS" originated from Nitto1320 Challenge, where we painted oS on our cars while on the team OldSchoolRacing, and even use oS on our cars to show that we've been playing for a long time and say it in chats across the web to this day. A note, oS should not be said in real life, you just say "Old School".