The key parts of a Pen Device are Pen, Tablet Plate and an optional Cordless Mouse. Tablet Plate may be stand-alone or be embedded in another device such as a keyboard; and the Pen may be connected to Tablet Plate with a cord (corded), or be free from it (cordless). The figure below uses a Pen Tablet with USB interface as an example to show the key parts of a Pen Device.
Note: The optional Cordless Mouse requires a Pen Tablet with USB Interface.