Which of the following is not one of the four main stages of the product design process?

In the context of the product design process, it is essential to understand the typical stages that designers follow to bring a concept to fruition. The four main stages often include Research, Develop, Design, and Test. Research involves gathering information to understand user needs and market demands, while Development focuses on creating solutions based on insights gained during research. Testing validates whether the design meets the required specifications and user expectations.

The stage of "Prototype," while an important aspect of the design process, is generally considered part of the Development phase rather than a standalone main stage. Prototyping is the act of creating preliminary models or mock-ups to visualize and evaluate the design concepts, but it does not encompass the entirety of the design process in the way that the other stages do. Therefore, recognizing the role of prototyping helps clarify its position within the broader framework of product design.