As stated at the beginning of chapter 3 the designer's brief is to develop a form such that an artifact constructed according to this form would satisfy the requirements. The form is the design. The ultimate output of a design process must, then, be an explicit description or representation of the form in some abstract or symbolic language. I shall use the term design description to refer to such symbolic representations of forms. When ‘design’ is used as a noun it becomes essentially a synonym for ‘form’.

The concept of form is elusive, abstract, and complex. It may refer to the visible shape of an entity – as when naturalists and biologists talk of biological forms. It may refer to the essential or ultimate nature of a thing – as when philosophers talk of Platonic forms. It may denote the way in which certain parts are arranged and related to one another in an entity – as when one talks of the form of an essay, an argument, a solution, or a musical composition. Finally, architects talk of forms or ‘built’ forms (March 1976, Alexander 1964) in which term they embrace in a complex, diffuse fashion, the totality of shape, structure and relationships of parts as manifested in buildings.

These examples clearly reveal that form as a general concept is multifaceted. Thus, when we undertake to design an artifact the end product of our activity – the form of the artifact itself and how it is to be described – is critically dependent on how or for what purpose the design is to be used.