Vista also aims to increase the level of communication between machines on a home network, using peer-to-peer technology to simplify sharing files and digital media between computers and devices. Windows Vista includes version 3.0 of the NET Framework, which aims to make it significantly easier for software developers to write applications than with the traditional Windows API.

Microsoft's primary stated objective with Windows Vista, however, has been to improve the state of security in the Windows operating system. One common criticism of Windows XP and its predecessors has been their commonly exploited security vulnerabilities and overall susceptibility to malware, viruses and buffer overflows.

Microsoft began work on Windows Vista, known at the time by its codename Longhorn in May 2001, five months before the release of Windows XP. It was originally expected to ship sometime late in 2003 as a minor step between Windows XP and Blackcomb, which was planned to be the company's next major operating system release. Gradually, "Longhorn" assimilated many of the important new features and technologies slated for Blackcomb, resulting in the release date being pushed back several times.

Many of Microsoft's developers were also re-tasked to build updates to Windows XP and Windows Server 2003 to strengthen security. Faced with ongoing delays and concerns about feature creep, Microsoft announced on August 27, 2004 that it had revised its plans.

The original Longhorn, based on the Windows XP source code, was scrapped, and Longhorn's development started anew, building on the Windows Server 2003 Service Pack 1 codebase, and re-incorporating only the features that would be intended for an actual operating system release. Some previously announced features such as WinFS were dropped or postponed, and a new software development methodology called the Security Development Lifecycle was incorporated in an effort to address concerns with the security of the Windows codebase.