A device driver is a program that controls a device. Every device, whether it be a CD-ROM, network card, or sound card, must have a driver program.
Many device drivers come with the operating system.
For other devices, you may need to load a new driver when you connect the device to your computer. A device driver 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 knows. In contrast, most programs access devices by using generic commands. Therefore The device driver accepts generic commands from a program and then translates them into specialized commands for the device.