Microsoft Windows is a series of software
operating systems and graphical user interfaces produced by Microsoft.
Microsoft first introduced an operating environment named Windows in
November 1985 as an add-on to MS-DOS in response to the growing
interest in graphical user interfaces (GUIs). Microsoft Windows came to
dominate the world's personal computer market, overtaking Mac OS, which
had been introduced previously.
Unix (officially trademarked as UNIX, sometimes
also written as Unix with small caps) is a computer operating system
originally developed in 1969 by a group of AT&T employees at Bell
Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas
McIlroy, and Joe Ossanna.