Master Boot Record
The Master Boot Record is the first sector of a PC disk. It contains the first stage of the boot loader and a partition table. A valid MBR ends with the byte sequence
During booting the PC BIOS loads the MBR at linear address 0x7c00 and passes control to it (at real mode address 07c0:0000, or sometimes 0000:7c00). The MBR code is responsible for loading the rest of the boot loader, which then loads the operating system.