Master Boot Record (MBR)

What is Master Boot Record (MBR)?
The master boot record is a category of boot sectors and the very first sector found in computer mass storage media such as hard drives and removable media.

The master boot record contains information about loading the operating system and also about the partition of the hard disk. The programs contained in the master boot record determine which partition must be used when booting. The master boot record is missing on non-partitioned devices such as super disks, floppy disks, or other devices configured this way.
A master boot record has the following properties: It is always located in the first sector of the hard disk. Cylinder 0, Head 0, Sector 1 is the specific address of the master boot record on the hard disk. It contains information about the organization of the partitions and the file system. A master boot record is generally 512 bytes or more.

Using the FDISK or MBR command, users can create a master boot record in DOS and Windows systems. The master boot record can work as a chain boot loader regardless of the operating system. The three main components of the master boot record are the master partition table, the master boot code, and the disk signature. A damaged master boot record can be repaired in Windows 7 and Windows Vista using the “bootrec” command available in System Recovery Options.

In Windows XP, the repair command is “fixmbr.” One of the newest alternatives to the master boot record is the GUID partition table. It is a component of the uniform upgradeable firmware interface specification.