The term multimedia is now one of the most important keywords of modern society. This is a leading-edge field for computer technology, but has drastically different characteristics from the conventional computer technology from various standpoints.

At one time in the past, the computer was, literally speaking, a machine for 'computing'. If its source is traced back, it is found that there was an interest in knowing how much a machine would be able to approach man's intelligence, i.e. logical thinking. As a consequence, the computer is an artificial 'brain', and we have been thinking of the computer by using 'brain' as metaphor.

However, if we try to apply this metaphor to the computer of the multimedia age, we realize that it does not work from many perspectives. This is because multimedia technology appears to be developing in a direction somewhat different from the direction for artificially creating a highly intelligent machine called the brain.