A driver is software that allows your computer to communicate with hardware or devices. Without drivers, the hardware you connect to your computer—for example, a video card or a printer—won't work properly.
In most cases, drivers come with Windows or you can find them by going to Windows Update in Control Panel and checking for updates.
If Windows doesn't have the driver you need, go to the Windows 7 Compatibility Center website, which lists thousands of devices, and has direct links to driver downloads. Also, you can often find drivers on the disc that came with the hardware or device you want to use, or on the manufacturer's website.
For more information, see Update a driver for hardware that isn't working properly.