Microsoft's Windows XP reached its 25th anniversary of being released to manufacturing on 24 August 2001, marking the moment the company finally merged its consumer and business operating system lines under the Windows NT codebase. XP replaced Windows ME for home users and Windows 2000 for professionals, offering far greater stability than its predecessors along with a redesigned Start Menu, taskbar and overall interface that shaped how Windows looked for years afterwards.

Despite official extended support ending in April 2014, XP proved remarkably persistent: Microsoft was still patching security flaws in embedded and specialist versions as late as 2024, and organisations including 90 per cent of the UK's NHS were still running it in 2016, while India's central bank pushed banks to remove it from ATMs by 2019. Launched at retail in October 2001 in Home and Professional editions, XP is widely regarded by many users as a high point for Windows, remembered fondly for its stability and the iconic "Bliss" wallpaper, even as the disappointing Windows Vista followed soon after.