what is Device Driver

In computing, a device driver (commonly referred to as simply a driver) is a computer program that operates or controls a particular type of device that is attached to a computer.^[1] A driver provides a software interface
to hardware devices, enabling operating systems and other computer
programs to access hardware functions without needing to know precise
details of the hardware being used.

A driver typically communicates with the device through the computer bus or communications subsystem to which the hardware connects. When a calling program invokes a routine
in the driver, the driver issues commands to the device. Once the
device sends data back to the driver, the driver may invoke routines in
the original calling program. Drivers are hardware-dependent and operating-system-specific. They usually provide the interrupt handling required for any necessary asynchronous time-dependent hardware interface