Firmware is a category or class of memory chips which contain information that is permanent (meaning it isn’t erased when you shut off your computer or when the power suddenly goes out on a dark and stormy night). The best examples of firmware are the ROM chips in your computer that contain programs installed at the factory. Firmware cannot be altered, per se, but in some cases the whole chip can be completely replaced by a technician when it becomes outdated or obsolete.
Examples include the BIOS of a PC, the head-positioning software embedded within a HARD DISK drive or the error correcting and compression software within a MODEM. The name is meant to suggest something midway between hardware and software. There is an increasing tendency to place firmware into FLASH MEMORY rather than ROM so that it can be updated by the end user whenever improved versions become available, by running an installation program from a floppy disk or CD: