“Medium” is a word from the ancient language Latin. Medium stands for “middle”.
The plural form is media.
Media are vehicles that allow transmitting of information across space and/or time. The oldest and most essential medium of mankind is language.Deduced from language is writing. Writing is a picture medium, like for example a drawing or a sketch. Furthermore we distinguish between auditory media and visual media.
If technical equipment is needed in order to use or access the information delivered by a certain medium, then one speaks of technical media. If this equipment is electronic equipment, they are called electronic media. If the media work
digitally, then we talk of digital media.

In addition we distinguish between:
• Individual media (for example telephone, email, letter ...)
• Mass media (for example television, radio, journal...)
• One-directional media (information flows from sender to receiver only)
• Two-directional media (info flows from sender to receiver and back).
   - Mass media are mostly one-directional media while individual media are in most cases two-directional media
   -The Internet can be considered as a mixed form, somewhere between mass media and individual media.

What is symbolic coding ?
In order to be transmitted through media information must always be transformed to symbols first. Because transmitted is not the information itself,but only the symbols, that represent it (as for example characters, voltage
changes, bits and bytes, etc...). During this process of transformation to symbols information can be lost.
  -The transmission of information via media always requires a form of symbolic coding of this information              before transmission.
  -No transmission without symbolic coding !
After the transmission, the symbols must be converted back again into the original information. This is mostly done by technical equipment and/or through the human brain. Also at this stage information can disappear or be modified.
During the process of human perception, the information that has earlier been transmitted by media, now is being converted into mental representations, before it can be stored in the brain. At this stage it is very likely again, that some of the information disappears or is being modified in some way.
 -The human brain can neither store original information, nor can it store symbolic code (intended for media transmission). The only thing it can store are mental representations, formed during the process of perception !

What is multimedia ?
Multimedia is mostly understood as a combined and graphically integrated presentation of conventional media forms, such as pictures, graphic, photo, animation, video, audio and further forms. Today this can be achieved well with the aid of digital and computer technology.But Multimedia is possible also without the use of computers. In this sense apictured periodical would also be “Multi Media”, just like television or video. However, this is not typically referred to as Multimedia.

What is interactive multimedia ?
If the user has the additional possibility of interactively selecting the multimedia information provided, this is called interactive multimedia.

What is hypertext ?
Hypertext is an electronic form of text information on a screen medium, where the user has the possibility to jump to another place within the same text or to another text by clicking on ‘hot words’ or links (?? Interactivity).
 -The World Wide Web (WWW) is the best known example of hypertext

What is hypermedia ?
If it is possible in a hypertext to not only jump to another text position, but also to another media form, as for example picture, audio, video, animation, etc..., then we talk of hypermedia instead of hypertext.
-The presentation is not graphically integrated in most cases

What are conventional media forms ?
Conventional media forms are such media forms, which have been developed along with the evolution of the human civilization. They were developed one after another with big time spans between the different developments and
mostly independent from each other.

Conventional media forms in the historical sequence of their development:
• Language (spoken)
• Drawing (pictures, graphic art)
• Writing (text)
• Printing (text)
• Photography
• Audio (words and music; first transmission, later recording)
• Motion pictures (film, video; first recording, later transmission)
• Animation (2D and 3D)

Over the centuries each media form mentioned has developed a separate tradition of creation and production, which we as users/observers regard as given and natural. But we would almost always notice violations against these
traditions immediately. Media creators must always respect and learn the respective tradition of each
conventional medium, before they can create contents professionally for this target medium.
Within the framework of media integration the particularchallenge for content creators and media producers consists in having to work themselves into several of these traditions before they can go ahead and do media integration
in a professional way.

from : Prof. Dr. Roland Riempp