How does BIOS find and load OS?

The BiOS (Basic Input/Output System) initializes hardware components during the boot process and performs a Power-On Self-Test (POST) to ensure everything is functioning correctly. It then identifies and accesses the bootable devices, typically prioritizing them based on the boot order set in its configuration. Once a bootable device is found, the BiOS reads the boot sector, which contains the bootloader, and transfers control to it. The bootloader then loads the operating system into memory, allowing the system to start up.