We propose a description of product design based on four design spaces. These design spaces correspond to particular representations of the product (need, perception, function and physical representation) which are more or less adapted to the designers and users preoccupations and to the successive stages of the design process. We show that this definition allows the representation of four characteristic design processes, starting from non-explicit needs until the end-products, by specific circulations throughout the design spaces. The most complete design process, is composed of five elementary design stages. After a description of different theories and methods useful within the design process, we show how these five design stages may be convenient to naturally locate and connect them.