Abbreviation for NT (as in Windows NT) File System or New Technology File System, depending upon who you talk to. NTFS is the file storage system used under the Windows NT operating system, just as FAT-32 is the file system used other versions of Windows and HFS or HFS+ is used under the Mac OS. On fairly unique and important aspect of NTFS is that information about a file’s clusters and other data is stored with each cluster, rather that just in a governing table, such as FAT, which allows for some greater flexibility as far as where files are placed on the disk.