Deployment Tools Foundation is a rich set of .NET class libraries and related resources that together bring the Windows deployment platform technologies into the .NET world. It is designed to greatly simplify deployment-related development tasks while still exposing the complete functionality of the underlying technology.
The primary focus of DTF is to provide a foundation for development of various kinds of tools to support deployment throughout the product lifecycle, including setup authoring, building, analysis, debugging, and testing tools. In addition to tools, DTF can also be useful for install-time activities such as setup bootstrappers, external UI, and custom actions, and for application run-time activities that need to access the deployment platform.
For a description of the the latest changes, see What's New.