The primary role of firmware in hardware devices is to provide low-level control and management of the hardware components. It is a type of software that is embedded directly into devices such as routers, printers, and embedded systems, allowing them to perform specific functions. Firmware is essential for enabling hardware abstraction, allowing the operating system and applications to interact with the hardware without delving into hardware specifics. It is typically stored in a device's non-volatile memory and can often be updated to improve performance or fix bugs. Thus, firmware ensures smooth operation and functionality of hardware devices.