A Microsoft file system, used in Windows NT (2000, XP, Vista, 7, 8, 10)

NTFS (New Technology File System) is the standard file system of Windows NT, including its later versions Windows 2000, Windows XP, Windows Server 2003, Windows Server 2008, Windows Vista, and Windows 7.

NTFS supersedes the FAT file system as the preferred file system for Microsoft’s Windows operating systems. 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 (ACL) and file system journaling.

Source: http://en.wikipedia.org/wiki/NTFS

Ubuntu can read and write files on NTFS filesystems. This makes NTFS partitions useful as storage common to Ubuntu and Windows system partitions. Importantly, NTFS does not support Linux file permissions (though some control is possible by adjusting mount options) so it is not suitable for an Ubuntu root / or /home partition.