Firmware - definition

Firmware is a class of computer software that provides low level control-over of the associated hardware in the device. In other words it is said, firmware is a embedded software inside of a specific hardware in order to run other hardware which are necessary to run the device’s entire operation. In shorter term it is called as “Embedded Software”.
i.e.: A microcontroller, a part of microprocessor which tells the microprocessor what action to take and what instructions set to execute depending on the system’s need.