Windows Vista

Windows Vista is a major release of the Windows NT operating system developed by Microsoft. It was the direct successor to Windows XP, released five years earlier, which was then the longest time span between successive releases of Microsoft Windows. It was released to manufacturing on November 8, 2006, and over the following two months, it was released in stages to business customers, original equipment manufacturers (OEMs), and retail channels. On January 30, 2007, it was released internationally and was made available for purchase and download from the Windows Marketplace; it is the first release of Windows to be made available through a digital distribution platform.

Development of Windows Vista began in 2001 under the codename "Longhorn"; originally envisioned as a minor successor to Windows XP, it gradually included numerous new features from the then-next major release of Windows codenamed "Blackcomb", after which it was repositioned as a major release of Windows, and it subsequently underwent a period of protracted development that was unprecedented for Microsoft. Most new features were prominently based on a new presentation layer codenamed Avalon, a new communications architecture codenamed Indigo, and a relational storage platform codenamed WinFS — all built on the .NET Framework; however, this proved to be untenable due to incompleteness of technologies and ways in which new features were added, and Microsoft reset the project in 2004. Many features were eventually reimplemented after the reset, but Microsoft ceased using managed code to develop the operating system.