Windows XP: The market share behemoth
Release date: Oct. 25, 2001
Windows 2000 and Me were quickly succeeded by Windows XP, which merged the operating system product lines for consumers and businesses and is still by far the most widely used desktop OS. XP still runs on more than more than half of computers more than nine years after release, although usage is declining in response to Windows 7 deployments. Despite frequent security problems, Windows XP Professional became the de facto operating system for most business users with updated versions of Microsoft Office as well as "remote desktop support, an encrypting file system, system restore and advanced networking features."