Media types can be divided into simple and multimedia types. This may be by using a single word or phrase to a more complete description with examples. The advantage of this media type is that it can easily be indexed and searched. The drawback is of course that text is written in a language and thus not multi-lingual. An object may store the description in different languages though.
Symbols are a central part of the language.
The symbol itself does not hold any information about the object and thus has to be memorized. This task becomes easier if the symbol is an icon or symbols are designed according to basic underlying rules and concepts. Figure 2.23 on page shows one concept which was introduced by Maurer and Lennon. Symbols are the visual counterpart to words in written natural languages. However there is a significant difference.