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. The symbol represents the abstract idea, whereas a graphic shows one concrete entity. Whereas the word includes everything from a comfortable chair to a wooden stool the photo depicts only one example of a chair. If the photo is chosen carefully the user should be able to grasp the abstract idea of the entity depicted. There might be several graphics stored in an object, which makes it easier to grasp the meaning of the object by finding the common features of the graphics.