Gradually, Windows 'Longhorn' assimilated many of the important new features and technologies slated for 'Blackcomb', resulting in the release date being pushed back a few times. Vista's original codename, 'Longhorn', was an allusion to this plan: While Whistler and Blackcomb are large ski resorts in British Columbia, Longhorn is the name of a bar between the two mountains that Whistler's visitors pass to reach Blackcomb. Microsoft originally expected to ship the new version sometime late in 2003 as a minor step between Windows XP (codenamed 'Whistler') and the next planned major release of Windows, code-named 'Blackcomb'. Development of Windows Vista occurred over the span of five and a half years, starting in earnest in May 2001, prior to the release of Microsoft's Windows XP operating system, and continuing until November 2006.
