I was an intern in the WinFS team in 2004 - seriously nobody knew what it actually was even inside the team.<p>The best I could say was that it was a way for lots of applications writing their own complex datastores (like outlook) to share an OS-level platform so that it could be exposed to other applications with a unified API.  It was way more a developer tool than a user-facing feature, but that&#x27;s not how it was marketed.