This book presents a model (HUNE) that assists in the insertion of human aspects in the product development process (PDP), at the beginning of a project, at the analyzed information, during its development and post-development, evaluating its suitability for human beings. The model proved to be actual with respect to the existing ones, dynamic and flexible, because it does not replace any model, but can be applied to other models, methods, or structures of PDPs, and enables scope, replication, and future improvements. Its applications brought satisfactory results, and it was very well evaluated by the participants in the application, by external experts and also through scientific publications.