Is Microsoft Windows the youngest operating system?

Answer 1

No. Many systems have been released since Microsoft Windows. These include:

Linux - released in 1991 (predates Windows 3.1, NT, 95, 98, ME, 2000, XP, Vista)

Mac OS X - released in 1999 (predates Windows ME, 2000, XP, and Vista, but not 98)

BeOS - released in 1991 (predates Windows 3.1, NT, 95, 98, ME, 2000, XP, Vista)

AROS - initial release 1995 (predates Windows 98, ME, 2000, XP, Vista)

AtheOS / Syllable - publicly released in 2000 (predates Windows XP and Vista)

SkyOS - first beta released in 2004 (predates Windows Vista)

And, if you consider individual members of each family, many have releases newer than Vista:

Linux - Ubuntu 8.10 (released October, 2008), OpenSUSE 11.1 (released December, 2008)

Mac OS X - OS X 10.5 (released October 2007)

AROS - stable release (April 2007), daily testing releases

Sylalble - 0.65 (released January 8, 2008)

SkyOS - Build 6947 (released August. 2008)