The NTFS File System contains a key file named the Master File Table (MFT) that stores information about the volume. This core file contains an entry for every file on the volume and information about these files including size, time, date, permissions, etc.
For general information on the Master File Table, see:
As more files are added to the NTFS volume, the MFT will grow to handle the larger files. Very early versions of Windows would grow the MFT in small portions which would cause fragmentation. Later versions of Windows introduced an MFT zone reservation. This zone is a portion of the disk that is reserved for the MFT to grow into so that the MFT can remain continuous. These previous versions of Windows use a percentage based algorithm to determine the zone size (default of 12.5%). For information on earlier versions of Windows, see article: