Windows XP is a major release of Microsoft's Windows NT operating system. It was released to manufacturing on August 24, 2001, and later to retail on October 25, 2001. It is a direct upgrade to its predecessors, Windows 2000 for high-end and business users and Windows Me for home users, and is available for any devices running Windows NT 4.0, Windows 98, Windows 2000, or Windows Me that meet the new Windows XP system requirements.
Development of Windows XP began in the late 1990s under the codename "Neptune", built on the Windows NT kernel and explicitly intended for mainstream consumer use. An updated version of Windows 2000 was also initially planned for the business market. However, in January 2000, both projects were scrapped in favor of a single OS codenamed "Whistler", which would serve as a single platform for both consumer and business markets. As a result, Windows XP is the first consumer edition of Windows not based on the Windows 95 kernel or MS-DOS. Windows XP removed support for PC-98, i486 and SGI Visual Workstation 320 and 540 and will only run on 32-bit x86 CPUs and devices that use BIOS firmware.
Upon its release, Windows XP received critical acclaim, noting increased performance and stability (especially compared to Windows Me), a more intuitive user interface, improved hardware support, and expanded multimedia capabilities. Windows XP and Windows Server 2003 were succeeded by Windows Vista and Windows Server 2008, released in 2007 and 2008, respectively.
Mainstream support for Windows XP ended on April 14, 2009, and extended support ended on April 8, 2014. Windows Embedded POSReady 2009, based on Windows XP Professional, received security updates until April 2019. After that, unofficial methods were made available to apply the updates to other editions of Windows XP. Microsoft discouraged this practice, citing compatibility issues. However, over eight years from the end of life date (September 2022), the majority of PCs in some countries (such as Armenia) still appeared to be running on Windows XP.