A computer driver (or device driver) acts as an interface between an Operating System and a hardware device. Each hardware device (mouse, keyboard, graphics card, printer, etc) has different capabilities and options, some of which are unique to the device. A driver provides the information for an operating system to fully communicate and utilise all the available functions the device offers.
With modern Operating Systems as a device is plugged in, either through an external port or internal bus, a driver is automatically downloaded and installed. Sometimes a driver has to be installed