GRUB (GRand Unified Boot-Loader) is a very important part of your operating system. Although, technically, it’s not actually part of the OS itself, but rather integrates itself in to file system structure.
GRUB hasn’t really seen many visual changes over the course of its development. In fact, most visual changes have come from third party developers and operating systems attempting to blend GRUB in to the general theme of the OS.
GRUB is a pretty simple concept. It dumps the boot-loader code on to the first sector of the boot hard drive and boots any operating system it has been configured to boot. Whether it be Linux, BSD or Windows. It’s a great piece of small code that performs its job well.
GRUB legacy has been developed in to what is now commonly known as GRUB2. But before GRUB actually reached version 2, OS developers were including previous iterations which were 1.9x versions.
The GRUB developers have finally completed the final pieces of code that brings that actual version number from 1.9x to 2. I would expect to see GRUB2 being updated in most distributions soon.