Formerly known as Whistler, this newest version of Windows for consumers and businesses, is based on the NT/2000 microkernel code. It combines the more stable and powerful core of Windows 2000 with the high usability shell of Windows Me. The look of the operating system is based around 'themes' provided by Microsoft. It was originally intended as a mainly consumer version of Windows using the NT/2000 code base, as a means to replace the aging Windows 95/98/Me which are based on DOS and the Win32 API. XP is now also intended for businesses. It was released in October 2001.