OS Supplied Device Drivers

The Class Definition and Class Specification allows independent groups to work seperately on host software development and device development, but still allows the device and host software work without any interoperability issues. Most of the times the Operating Systems will implement default device drivers for most of the device classes introduced by USB-IF. The default device drivers reduce the burden on device manufacturers as they avoid spending time on development of device drivers. These device drives will be installed when the Operating System is installed on a host, and available for all devices that follow the class specifcation.

The other benifit of designing a device to follow a specific Device Class is, even if a Operating System does not support a device class in current version, there is a good chance that the class will be supported in next version.

To avoid Windows to show the Unknown Provider message, the vendor developed device drivers need to signed for Windows. If you are already using a Operating System supplied Class Driver then this activity can also be avoided.

So, overall apart form grouping devices which has common features, the device class also reduces the development time cycle by helping the Operating Systems also to do some work on device manufacturer's behalf.