The software that is required to support a particular device depends on the kind of device and the ways in which the device is used. Typically, a vendor provides the following software in a driver package to support a device:
A device setup information file (INF file)
An INF file contains information that the system Windows components use to install support for the device. Windows copies this file to the %SystemRoot%\inf directory when it installs the driver. This file is required.
For more information, see Creating an INF File.
One or more drivers for the device
A .sys file is the driver's image file. Windows copies this file to the %SystemRoot%\system32\drivers directory when the driver is installed. Drivers are required for most devices.
For more information, see Choosing a Driver Model.
Digital signatures for the driver package (a driver catalog file)
A driver catalog file contains digital signatures. All driver packages should be signed.
A vendor obtains digital signatures by submitting its driver package to the Windows Hardware Quality Lab (WHQL) for testing and signing. WHQL returns the package with a catalog file (.cat file).
For more information, see WHQL release signatures.
A driver package can contain other files, such as a custom device installation application, a device icon, or a driver library file (such as for video drivers).
Also, see the device-type-specific documentation in the WDK.
The WDK includes various sample installation files. For more information, see Sample Device Installation Files