Multimedia is defined by the Oxford English Dictionary as “Using more than one medium of communication, artistic expression, etc.; (Computing) designating or relating to applications which incorporate a number of media, such as text, audio, video, and animation, esp. interactively.”  Broken down, the term is made up of ‘multi’ meaning “‘more than one, several, many’”  and ‘media’ defined as “The main means of mass communication, esp. newspapers, radio, and television, regarded collectively; the reporters, journalists, etc., working for organizations engaged in such communication.”  Related to the term multimedia, and used interchangably, is the term mixed media, defined by the Oxford English Dictionary as “The use of more than one medium, as a painting technique; (more generally) the use of a variety of media in any creative work, entertainment, etc.”  Although these definitions provide a starting point for understanding the notion of multimedia, the term remains a thoroughly ambigious concept both theoretically and in common usage. In simply looking at the differences between the simple OED definion of media (plural term) cited above and the complex, multiple OED definitions of medium (singluar term), the true meaning of these terms becomes difficult to discern.  What is the difference between that which is called multimedia and that which exists as a singular medium? What are the limits/boundaries of these media designations?
Marshall McLuhan theorizes that all media are actually multimedia, that no media can exist in isolation. “The ‘content’ of any medium is always another medium. The content of writing is speech, just as the written word is the content of print, and print is the content of the telegraph. If it is asked, ‘What is the content of speech?,’ it is necessary to say, ‘It is an actual process of thought, which is in itself nonverbal.’”2 W. J. T. Mitchell agrees with McLuhan, claiming that “All media are mixed media.”  Mitchell however makes one slight modification to McLuhan’s media theory. While McLuhan claims that the content of a particular media has to be an older medium, Mitchell disagrees. Mitchell explains that where McLuhan “went wrong was in assuming that the ‘other’ medium has to be an earlier medium (novels and plays as the content of film, film as the content of video). The fact is that a newer and even nonexistent medium may be ‘nested’ inside of an older medium.”  According to McLuhan and Mitchell there are no boundaries that theoretically exist between the term media and multimedia, as all media are in actuality multimedia (or mixed media).
It is clear that there is a discontinuity between how the Oxford English Dictionary defines multimedia and how theorists like McLuhan and Mitchell address media. Why is this the case? Why are there essentially two terms (media and multimedia) that, according to McLuhan and Mitchell, describe the same phenomenon? The answer to this question lies in the way people experience and understand media. There is a difference in peoples’ conceptions or lack thereof of visible media and seemingly invisible media, as well as old media and new media. In general, people tend only to conceive of and refer to new media as multimedia.
First, there are what might be described as unnoticed or invisible media. Mitchell makes this clear when he profoundly claims that, “Minds [link] are media and vice versa. Mental life (memory, imagination, fantasy, dreaming, perception, cognition) is mediated and is embodied in the whole range of material media… We not only think about media, we think in them.”  Our very senses, so familiar and taken for granted, are hardly noticed by individuals. Therefore, as people, we forget that our perception itself is multi-modular; we perceive with two eyes, we hear with two ears, sense with two hands etc. “Our very word ‘grasp’ or ‘apprehension’ points to the process of getting at one thing through another, of handling and sensing many facets at a time through more than one sense at a time.”  Part of an individuals’ experience of media (including mental and sensual media) therefore, is unnoticed and this results in an incomplete picture of media.
In addition to the distinction between visible and unnoticed media, people tend to draw a distinction between old and new media, with new media being conceptualized as multimedia. Since the whole conception of media as ‘new’ is culturally specific and changes through time, distinctions between what is old and new are constantly being redefined. From a cultural perspective, old media is seen as traditional, common, and simple, while new media is conceived of as innovative, complex, exciting, and shocking. Indeed Mitchell is correct in claiming “The shock of new media is as old as the hills.” 
But how does new media emerge? McLuhan claims that “The hybrid or the meeting of two media is a moment of truth and revelation from which new form is born… The moment of the meeting of media is a moment of freedom and release from the ordinary trance and numbness imposed by them on our senses.”  Thus for example, when film (essentially a combination of moving photography and a screen]) emerged as a new medium, the spectator was shocked, astonished, and filled with wonder. “If not all the attractions of early cinema express the violence of an on-rushing train, some sense of wonder or surprise nonetheless underlies all these films, if only wonder at the illusion of motion.”  The same astonished reaction occurs today with the advent of new media.
Presently, people tend only to conceive of new media as being multimedia. Such multimedia includes the computer, video, websites, the internet, virtual reality, simulation, animation, and other digital technology. The label and use of multimedia has penetrated nearly all areas of society, including fields as distinct as art, medicine, and education. In art, multimedia performances and exhibitions are a common occurrence. One example of these multimedia performances is the dance performances choreographed by Merce Cunningham. These performances combine and are not limited to modern dance, music, artwork, photography, and even video. Cunningham uses innovative combinations of media to conceptualize new and exciting performances. One example of this innovation is the fact that, “Since 1989, Cunningham has used a 3-D motion creation software program called Life Forms and the cinematic technique of motion capture to map and experiment with movement. Both tools have shown the potential of liberating movement from a dancer’s body and propelling his/her “skeleton” or other corporeal “residues” into virtual space.” 
In addition to art, multimedia technology is also used in the fields of medicine and education. One use of such multimedia technology is to improve surgical techniques and other medical practices. Video endoscopy a technique in which a video camera is inserted into the human body to distinguish problems and even to perform surgery, is one example of such multimedia medical technology.  A common example of the surgical uses of video endoscopy is arthroscopic knee surgeries.  In this medical procedure, the endoscope is inserted into the knee and a live video feed of the knee interior is displayed on a television screen; the surgeon watches the television screen and coordinates his surgical movements according to the real-time video.
Education is another field into which multimedia technology has become prevalent. A new way of learning, frequently deemed “Edutainment,” (a term coined by Bob Heyman) has arisen in many learning environments, including museums. Museums notably have been shifting their exhibits to accommodate learning through multimedia technology.  “Multimedia kiosks were the first digital devices implanted in museum and continued to be installed. Those that are connected to the internet are the newest variety, but the tried-and-true models of the late 1980’s allow the visitor to retrieve information about collections in an environment reminiscent of a language lab.”  Multimedia technology is thus changing the nature of many institutions and fields of study, not to mention our everyday social life. Multimedia is inescapable; in essence “our relation to media is one of mutual and reciprocal constitution: we create them and they create us.” 
1. Oxford English Dictionary Online
2. McLuhan p.8
3. Mitchell p.215
4. Mitchell p.216
5. Mitchell p.215
6. McLuhan p.60
7. Mitchell p.213
8. McLuhan p.55
9. Gunning p.125
10. Merce Cunningham: In Conversation with John Rockwell.
11. See http://dave1.mgh.harvard.edu/
12. See http://patienteducation.upmc.com/ Pdf/KneeArthroscopy.pdf
13. See http://www.reference.com/browse/ wiki/Edutainment
14. Anderson p.148
15. Mitchell p.215
Anderson, Maxwell L. “Museums of the Future: The Impact of Technology on Museum Practices.” Daedalus 128.3 (1999): 129-162.
McLuhan, Marshall. Understanding Media: The Extensions of Man. Massachusetts: The MIT Press, 1994.
Merce Cunningham: In Conversation with John Rockwell. 2005 Stanford University Libraries. 26 Jan 2007. .
Mitchell, W.T.J. What Do Pictures Want?: The Lives and Loves of Images. Chicago: The University of Chicago Press, 2005.
Gunning, Tom. “An Aesthetic of Astonishment: Early Film and the (In)Credulous Spectator” Viewing Positions: Ways of Seeing Film. Ed. Linda Williams. New Brunswick: Rutgers University Press, 1997. 114-133.
Oxford English Dictionary. 2007 Oxford University Press. 26 Jan 2007. .