BIOS definition

BIOS (Basic Input/Output System) is a computer subsystem that starts the main system by detecting, configuring and sometimes testing hardware and then loads a boot loader (code) into the CPU which then may proceed to load an OS.

BIOS's therefore work like a starter in a internal-combustion-engine car or a pilot light in a gas fire, enabling it to boot after powering up or receiving a signal or message from a device while on standby. BIOS's are also used to check and manage the system with or without loading a OS or any other software. A BIOS chip is basically a small all-in-one pre-configured computer which stores data in an internal ROM, flash and/or battery-powered memory. Much of the firmware however can be updated or even replaced entirely.