Regarding Grub
 

What exactly Grub means ?? and how can we modify it ?

GRUB = "GRand Unified Bootloader"
It is the bootloader developed by the Open source community (specifically the Gnu Project) to replace LILO.
http://www.gnu.org/software/grub/

GRUB performs the same function as the Windows boot code.

When you say "modify", I think you mean change the behavior--this is done with the configuration file: /boot/grub/menu.lst

The "booting" link below might help, and their are lots of threads here at LQ--just search using "grub"

Quite informative article about GRUB -> http://www.linuxjournal.com/article/4622

Fedora Development

Hi
pixellany: thanks for replaying
prad77: ur link is helpfull
regards