NTFS is the standard file system of Windows NT, including its later versions Windows 2000, Windows XP, Windows Server 2003, Windows Server 2008, and Windows Vista.
NTFS replaced Microsoft's previous FAT file system, used in MS-DOS and early versions of Windows.
NTFS has several improvements over FAT and HPFS (High Performance File System) such as improved support for metadata and the use of advanced data structures to improve performance, reliability, and disk space utilization plus additional extensions such as security access control lists and file system journaling.
The exact specification is a trade secret, although (since NTFS v3.00) it can be licensed commercially from Microsoft through their Intellectual Property Licensing program.
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