What is Master Boot ?

The Master Boot Record (MBR) is the first 512 bytes of a storage device. It contains an operating system bootloader and the storage device’s partition table

During the first stage of the boot process, the BIOS (basic input output system) searches for the MBR and then loads it into memory, after which the MBR takes over

identifies how and where an operating system is located so that it can be boot (loaded) into the computer’s main storage or random access memory