What is GRUB (GRand Unified Bootloader)?
GRUB is a bootloader that is used to load the Linux kernel and init system on boot. It allows users to select the operating system or kernel to boot from a menu, as well as set various boot options. The GRUB configuration file, located at “/etc/default/grub”, contains various options that control the behavior of the bootloader. By editing this file, you can customize the appearance and behavior of the GRUB boot menu.