The master boot record on a hard drive contains the necessary computer code to start the boot process.
The master boot record is created when a hard drive is partitioned but is not located within a partition. The master boot record is located on the first sector of a disk. The specific address on the disk is Cylinder: 0, Head: 0, Sector: 1.
In Windows 7 and Windows Vista, you can repair a corrupted master boot record using the bootrec command from System Recovery Options.
In Windows XP, the master boot record can be repaired using the fixmbr command. See How To Repair the Master Boot Record in Windows XP for help.
A volume boot record is another type of boot sector.