BIOS, Pronounced "bye-ose". This is an acronym for basic input output system.
The BIOS runs as part of the start up sequence when you switch on your computer. The BIOS contains all the code required to control the hardware e.g. keyboard, monitor, mouse.
The BIOS is stored seperately from the hard disk on a ROM chip. This means that if the computer crashes, the BIOS data is protected.