Windows XP is a line of operating systems produced by Microsoft for use on
personal computers, including home and business desktops, laptops, and media
centers. The name "XP" is short for "experience". Windows XP is the successor to
both Windows 2000 Professional and Windows Me, and is the first
consumer-oriented operating system produced by Microsoft to be built on the
Windows NT kernel and architecture. Windows XP was first released on October 25,
2001, and over 400 million copies were in use in January 2006, according to an
estimate in that month by an IDC analyst. It was succeeded by Windows Vista,
which was released to volume license customers on November 8, 2006, and
worldwide to the general public on January 30, 2007. Direct OEM and retail sales
of Windows XP ceased on June 30, 2008. Microsoft continued to sell XP through
their Custom built PC (smaller OEMs who sell assembled computers) until January
31, 2009. XP may continue to be available as these sources run through their
inventory or by purchasing Windows Vista Ultimate or Business and then
downgrading to Windows XP.
The most common editions of the operating system are Windows XP Home Edition,
which is targeted at home users, and Windows XP Professional, which offers
additional features such as support for Windows Server domains and two physical
processors, and is targeted at power users, business and enterprise clients.
Windows XP Media Center Edition has additional multimedia features enhancing the
ability to record and watch TV shows, view DVD movies, and listen to music.
Windows XP Tablet PC Edition is designed to run stylus applications built using
the Tablet PC platform. Windows XP was eventually released for two additional
architectures, Windows XP 64-bit Edition for IA-64 (Itanium) processors and
Windows XP Professional x64 Edition for x86-64. There is also Windows XP
Embedded, a component version of the Windows XP Professional, and
editions for specific markets such as Windows XP Starter Edition. By mid 2009, a
manufacturer revealed the first Windows XP powered cellular telephone.
The NT-based versions of Windows are known for their improved stability and
efficiency over the 9x versions of Microsoft Windows. Windows XP presents a
significantly redesigned graphical user interface, a change Microsoft promoted
as more user-friendly than previous versions of Windows. A new software
management facility called Side-by-Side Assembly was introduced to ameliorate
the "DLL hell" that plagues 9x versions of Windows. It is also the first version
of Windows to use product activation to combat illegal copying, a restriction
that did not sit well with some users and privacy advocates. Windows XP has also
been criticized by some users for security vulnerabilities, tight integration of
applications such as Internet Explorer 6 and Windows Media Player, and for
aspects of its default user interface. Later versions with Service Pack 2,
Service Pack 3, and Internet Explorer 8 addressed some of these concerns.
During development, the project was codenamed "Whistler", after Whistler,
British Columbia, as many Microsoft employees skied at the Whistler-Blackcomb ski resort.
As of the end of June 2009, Windows XP is the most widely used operating
system in the world with a 66.9% market share, having peaked at 76.1% in January
According to a Net Applications report, the Windows XP market share peaked as
high as 85.3% in December 2006.