According to McLuhan, all mediums can be classified as either "hot" or "cool". The main distinction between a hot or cold medium is the amount of information provided and the amount that is left for the audience to fill in. A hot, or high definition medium such as the radio or a film is dense in information and require less to be completed by viewer. A hot medium is low in participation, while a cool medium such as a cartoon or a telephone is high in participation, or required completion and therefore has a very different effect on the user. A telephone conversation for example, leaves much to be interpreted by the individual.