1. NT File System. An optional way of formatting disks under WinNT that contains many enhancements (performance, reliability, and security) over the older FAT file-system found in DOS. Key point: Hardened WinNT computers should use NTFS exclusively. After installation, some file and directory permissions need to be adjusted. Key point: NTFS supports a feature called "alternate data-streams" (similar to Macintosh data and resource forks) that can be used to attach data to files in a hidden way. The additional information does not appear to change the size of the file in directory listings. From Hacking-Lexicon