Device driver

A device driver is a software module in an operating system which is an intermediary between the rest of the system, and the actual peripheral itself. It knows which instructions to use to cause the device to perform the actions of which it is capable, and handles any interrupts from the device (generated either when an error happens, or when some requested action is completed).

Usually operating systems have an interface specified which device drivers need to use, to allow both the OS, and users, to make use of the device.