Storage Technologies
System class and filter drivers for storage devices act as an interface between any intermediate-level or highest-level drivers that are layered above the class or filter driver and a system-supplied port driver. For example, if the USB bus driver enumerates a device that complies with the mass storage class on a computer that is running Windows, that enumeration automatically loads the USB storage port driver (usbstor.sys) for that device.
Consumer devices often integrate removable media products such as Compact Flash or Secure Digital (SD), and new PCs often include support for such removable media. Windows file system and driver support for such devices includes native support for devices that comply with the USB Mass Storage Class Specification.