A physical transmission medium such as optical fiber
A presentation medium (and thus the terms multimedia and advertising media)
In his influential book, Understanding Media , Marshall MacLuhan said "The medium is the message." He seemed to mean that media technology itself transformed our lives more than the messages the media carried. He saw radio as a "hot medium" that imposed itself on you and television as a "cool" medium that pulled you into it. He envisioned that television would foster an electronic world community, a "global village." Although he wrote before the Internet became widely known, the Internet almost seems like his best idea.