(WINdows Future Storage) The code name for an object-oriented unified storage subsystem that runs on top of the NTFS file system. WinFS was initially expected in Windows Vista, but was not included in the first release of the operating system.

WinFS uses a relational database and XML meta-data to go beyond the hierarchical view that Explorer presents to the user. It lets users index and combine heterogeneous data formats such as files, folders, e-mail messages and name/address contacts into groups. Data can be searched like a Google or Yahoo! search engine, which yields results in different formats (HTML pages, PDF files, Word documents, etc.).

FS Is Not a File System
Because "FS" are the last letters of the name, it has often been mistaken for a new file system that would replace NTFS. WinFS sits on top of NTFS and provides a programming interface (API) that software vendors can write to. From its first announcement, WinFS was considered an important new feature in Windows. See Windows Vista and NTFS.