GRUB 2 in default Boot Loader for Ubuntu and many other operating system now. Grub 2 introduces many new welcoming changes. Grub 2 is almost complete re-writing of Grub interface. Grub 2 in more modular and portable than its earlier version. It support dynamic loading of modules. If we talk about look, Grub2 is going to include Theme support. If you working on latest releases of Ubuntu you may become little bit confused because Grub2 working is diffrent from Grub 0.9(Old grub version).
How GRUB 2 Works ?
Grub2 layout is totally diffrent. Grub2 places its core files on three locations./boot/grub/grub.cfg, /etc/grub.d and /etc/default/grub. You may need to edit /etc/default/grub which contains customization and/or /etc/grub.d/ files which contain Menu information and booting scripts. You shouldn't edit grub.cfg file directly but when the update-grub command is run, it reads the contents of the grub file and the grub.d scripts and creates the grub.cfg file.