Answer:
Device drivers are a set of software instructions that control the interface between a computer and a connected peripheral device. Device drivers tell your machine what the device is, what the device does, and all the other instructions needed for proper operation. For instance, Windows™ does not ship with a specific device driver set for all the features in your new Logitech keyboard that has custom buttons.
Ref:
http://www.driverstorer.com/help.html