Microsoft Windows XP was introduced in 2001 and is the most significant upgrade to the Windows operating system since Windows 95. The previous version of Windows, called Windows Me (or Millennium Edition) still had the look and feel of Windows 95 and was known to have stability issues and incompatibilities with certain hardware.
Windows XP addressed many issues of its predecessor and added a number of other improvements as well. It is a stable operating system since it is built on the Windows 2000 kernel, which is known for its reliability. XP also has a new, more modern look, and an interface that is more easy to navigate than previous versions of Windows. While not written from the ground up, like Mac OS X, Windows XP is a substantial system update. The letters "XP" stand for "eXPerience," meaning the operating system is meant to be a new type of user experience.