GRUB, or the GRand Unified Bootloader, is a program that installs to your Master Boot Record and controls what operating system you load at boot time. Normally, it is used for multi-boot systems.
On many Linux systems the boot process sees the usual BIOS screen, followed by Grub. The Grand Unified Bootloader (Grub) takes over from our BIOS and offers the user a choice of OS options and kernel ...