Windows XP is an operating system produced by Microsoft as part of the Windows NT family of operating systems. It was the successor to both Windows 2000 for professional users and Windows Me for home users. It was released to manufacturing on August 24, 2001, and broadly released for retail sale on October 25, 2001.

Development of Windows XP began in the late 1990s as "Neptune", an operating system (OS) 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 scrapped in favor of a single OS codenamed "Whistler", which would serve as a single OS platform for both consumer and business markets. As such, Windows XP was the first consumer edition of Windows not to be based on MS-DOS.[5]

Upon its release, Windows XP received critical acclaim, with critics noting increased performance and stability (especially in comparison to Windows Me), a more intuitive user interface, improved hardware support, and expanded multimedia capabilities. However, some industry reviewers were concerned by the new licensing model and product activation system.[6]

Extended support for Windows XP ended on April 8, 2014, after which the operating system ceased receiving further support or security updates (with exceptional security updates, to address major malware threats, such as BlueKeep) to most users. Windows Embedded POSReady 2009, based on Windows XP Professional, received security updates until April 2019. Unofficial methods were made available to apply the updates to other editions of Windows XP. Microsoft officially discouraged this practice, citing incompatibility issues.[7]

As of March 2021, 0.7% of Windows PCs run Windows XP,[8] and 0.23% of all devices across all platforms run Windows XP. At least one country still has double-digit use, Armenia, where it is being replaced by Windows 10, while Windows XP has over 50% use.