There are a number of security and safety features new to Windows Vista, most of which are not available in any prior Microsoft Windows operating system release. Beginning in early 2002 with Microsoft's announcement of its Trustworthy Computing initiative, a great deal of work has gone into making Windows Vista a more secure operating system than its predecessors. Internally, Microsoft adopted a "Security Development Lifecycle" with the underlying ethos of "Secure by design, secure by default, secure in deployment". New code for Windows Vista was developed with the SDL methodology, and all existing code was reviewed and refactored to improve security.
