Modality

• In music, modality is the subject concerning certain diatonic scales known as "modes" (e.g., Ionian). See musical mode.

• In language, modality is the subject concerning so-called "modal verbs" like can, must, and should, that are customarily used to modify the meaning of other verbs (which in turn tend to take the infinitive). Modal verbs express possibility (and impossibility, necessity, contingency, etc.), permissibility (and obligation, proscription, etc.), probability (and improbability, etc.). See grammatical mood.

• In philosophy, modal logic is a form of logic which distinguishes between (logically) "necessary truths" and "contingent truths". Related topics are possibility, impossibility, actuality, and related predicates.

• In computer science and particularly computer vision, modality refers to the type of input. That is, black-and-white, color and infrared are three different modalities for the acquisition of an image.

• In human-computer interaction, a modality is a path of communication between the human and the computer, such as vision or touch.

• In medical imaging, a modality is any of the various types of equipment or probes used to acquire images of the body. Radiography, ultrasound and magnetic resonance imaging are examples for modalities in this context.

• See also mode.