Windows XP is a personal computer operating system produced by Microsoft as part of Windows NT family of operating systems. Development of XP began in the late 1990s as "Neptune", an operating system built on the Windows NT kernel which was intended specifically for mainstream consumer use—an updated version of Windows 2000 was also originally planned for the business market. However, in January 2000, both projects were shelved in favor of a single OS codenamed "Whistler", which would serve as a single OS platform for both consumer and business markets. The operating system was released to manufacturing on August 24, 2001, and generally released at for retail sale on October 25, 2001.
Windows XP was a major advance from the 9x versions of Microsoft Windows in security, stability and efficiency due to its Windows NT underpinnings. It introduced a significantly redesigned graphical user interface and was the first version of Windows to use product activation in an effort to reduce software piracy.January 2006, over 400 million copies of Windows XP were in use.
According to web analytics data generated by Net Applications, Windows XP was the most widely used operating system until August 2012, when Windows 7 overtook it. In January 2014, Net Application reported a market share of 29.23% while W3Schools reported a share of 11.0%.
Sales of Windows XP licenses to most OEMs ceased on June 30, 2008, although until October 22, 2011, Microsoft continued to provide OEM licenses for use on "ultra low-cost" devices such as netbooks to compete against those running Linux-based operating systems. Despite its succession by newer versions of Windows, use of XP (particularly in enterprise environments) remained widespread due to the poor reception of XP's direct successor, Windows Vista. Although Microsoft products typically only receive ten years of support per its lifecycle policy, and "Mainstream" support for XP ended on April 14, 2009, "Extended" support for XP will end on April 8, 2014, after which Microsoft will no longer provide any more security patches or support information for XP, unless customers have a paid, "Custom" support plan. The looming end of support has been cause for concern due to large contingents of XP users in several categories, including enterprise environments, automated teller machines, and in China.
