What is the difference between the role of the GNU GRUB bootloader and the main BIOS during system startup?

BIOS is the basic input-output system that initializes hardware when the computer is turned on and performs basic tests (POST). Its task is to prepare the system for loading the operating system.

GNU GRUB is a bootloader that starts after BIOS and is responsible for selecting and loading a specific operating system or kernel. GRUB provides a menu for selection, supports multiple OS booting, and can pass parameters to the kernel.

In summary:

• BIOS initializes hardware and hands over control to the bootloader.
• GRUB loads and starts the OS, offering flexibility in choosing and configuring the boot process.