A device is an actual physical component, such as a router or printer or other equipment to which one or more IP addresses are assigned.
Devices are organized by device types and device sub-types. A device type is a general category of devices; a device sub-type is a more specific category of devices. For example, a general device type might be Printers. More specific device sub-types might include Laser Printers, Plotters, and Imagesetters.