grub 2.06 GRand Unified Boot loader
GRUB is a multiboot bootloader. It is used for initially loading the kernel of an operating system and then transferring control to it. The kernel then goes on to load the rest of the operating system. As a multiboot bootloader, GRUB handles the presence of multiple operating systems installed on the same computer; upon booting the computer, the user is presented with a menu to select one of the installed operating systems.