A Master Boot Recor (MBR), or partition sector, is the 512-byte boot sector that is the first sector ("Sector 0") of a partitioned data storage device such as a hard disk. (The boot sector of a non-partitioned device is a Volume Boot Record, these are usually different, although it is possible to create a record that acts as both; it is called Multi Boot Record.) The MBR may be used for one or more of the following: