firmware : Computer Hardware Buyers’ Glossary
Software is notoriously fragile. Just a tiny slip and it is lost. Some programs are
so important that they are burned into the equipment in a way that makes them hard to
lose. For example the BIOS (Basic Input Output System) on your
motherboard and the program that controls your router will live in firmware. It will
not be lost, even if the power goes off. Firmware can still be modified by special
procedures, usually they never change.