A program that controls a device. Every device, whether it be a printer, disk drive, or keyboard, must have a driver program. Many drivers, such as the keyboard driver, come with the operating system. For other devices, you may need to load a new driver or drivers when you connect the device to your computer. In Windows environments, driver or drivers often have a .DRV extension.
 
A driver or drivers acts like a translator between the device and programs that use the device. Each device has its own set of specialized commands that only its driver or drivers knows. In contrast, most programs access devices by using generic commands. The driver or drivers, therefore, accepts generic commands from a program and then translates them into specialized commands for the device..