Just as spoken languages are the basis for our conversations with people, so design languages are the basis for our interactions with products and services. Spoken languages consist of words and rules of grammar. By analogy, design languages consist of design elements and guidelines for their combination. People use spoken language to express themselves. Product designers use design languages to design expressive objects. When a designer uses a design language to design a product, the resulting product expresses what it is, what it does, how it is to be used, and the experiences to which it has the potential to contribute. When people use a design language to use a product, the resulting experience of use is simple and straightforward. The best design languages take the design of experience on step further by making interactions between people and objects pleasant and continuously meaningful. Design languages play a very important role in the expression of the “unfolding of meaning” of objects. 

[Fonte: Usability, Paul S. Adler & Terry A. Winograd,

Oxford University Press, 1992, pg. 18]