answer: Phonograph records are generally described by their diameter in inches (12-inch, 10-inch, 7-inch, etc.), the rotational speed at which they are played ("33 rpm ", "78", "45", etc.), their time capacity ("long playing"), their reproductive accuracy, or " fidelity " ("high fidelity", "Orthophonic", "full-range", etc.), and the number of channels of audio provided (" mono ", " stereo ", " quadraphonic ", etc.).