From Fedora Project Wiki
I would like to talk about the boot process involved.
GRUB2 (GNU GRand Unified Bootloader)
Briefly, boot loader is the first software program that runs when a computer starts. It is responsible for loading and transferring control to the operating system kernel software (such as the Hurd or the Linux). The kernel, in turn, initializes the rest of the operating system (e.g. GNU).
Currently GRUB 2 is under development, GRUB 2, has replaced what was formerly known as GRUB (i.e. version 0.9x), which has, in turn, become GRUB Legacy.
GRUB 2 aims at merging sources from PUPA in order to create the next generation of GNU GRUB.
GRUB Legacy is no longer being developed.