There are lot of grub questions lately and I was just about to answer one but somehow my answer turned out a bit long so I decided the change it into a more general post about grub and bootloaders. ….. I am going into a lot of details here about how a grub installation works. Please don’t take this a suggestion you should do it like this. Your distro will set this all up for you. I write about it because I think it helps to understand how grub works and because it allows repairing grub if it was damaged.

Full article here:
Short introduction into grub internals (reddit – linux4noobs)