Development of Windows Vista occurred over the span of five and a half years, starting in earnest in May 2001,[1] prior to the release of Microsoft's Windows XP operating system, and continuing until November 2006. Microsoft originally expected to ship the new version sometime late in 2003 as a minor step between Windows XP (codenamed "Whistler") and Windows 7 (codenamed "Blackcomb" and "Vienna"). 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.
