Windows XP is a version of the Microsoft Windows operating system for personal computers. The letters "XP" stand for eXPerience. Microsoft released Windows XP on October 25, 2001. Windows XP replaced Windows 2000 and Windows ME, which helped bring the NT and 9x versions of Windows together. It was replaced by Windows Vista in 2006. Windows XP was the second most used computer operating system in the world as late as April 2012. Following the release of Windows XP, many computer manufacturers including (but not limited to) Dell, Hewlett Packard, Acer, IBM, Compaq, and Toshiba rebadged their computers (mostly laptops) to Windows XP from Windows 2000. You can tell a laptop from that time was initially sold with Windows 2000 if the Windows (WIN) key on the keyboard has the previous Windows logo.
Microsoft stopped supporting Windows XP on April 8, 2014 (except some security updates e.g. in 2019, to address ransomware threats, and to address major malware threats, such as BlueKeep) and Microsoft and authorities warn users against using Windows XP. However, Windows XP remained a popular operating system around the world for a long time. On July 31, 2019, Microsoft Internet Games Services on Windows XP and Windows ME stopped working, and on January 22, 2020 Microsoft Internet Games Services stopped working on Windows 7, for Windows 8 and Windows 8.1 – on April 5, 2021. By August 2019, Microsoft (and others) had ended support for games on Windows XP. As of June 2021, 0.6% of Windows PCs run Windows XP. Windows XP became the most popular operating system from 2001 to 2007, the operating system, individually and pre-installed, selling over 500 million copies.