A design is a concept of either an object, a process, or a system that is specific and, in most cases, detailed. Design refers to something that is or has been intentionally created by a thinking agent, though it is sometimes used to refer to the nature of something. The verb to design expresses the process of developing a design. In some cases, the direct construction of an object without an explicit prior plan may also be considered to be a design (such as in some artwork and craftwork). The design usually has to satisfy certain goals and constraints; may take into account aesthetic, functional, economic, or socio-political considerations; and is expected to interact with a certain environment. Typical examples of designs include architectural and engineering drawings, circuit diagrams, sewing patterns and less tangible artefacts such as business process models. People who produce designs are called designers. The term 'designer' generally refers to someone who works professionally in one of the various design areas. Within the professions, the word 'designer' is generally qualified by the area of practice (so one may be, for example, a fashion designer, a product designer, a web designer, or an interior designer), but it can also designate others such as architects and engineers (see below: Types of designing). A designer's sequence of activities to produce a design is called a design process, using design thinking and possibly design methods. The process of creating a design can be brief (a quick sketch) or lengthy and complicated, involving considerable research, negotiation, reflection, modeling, interactive adjustment, and re-design. Designing is also a widespread activity outside of the professions, done by more people than just those formally recognised as designers. In his influential book The Sciences of the Artificial the interdisciplinary scientist Herbert A. Simon proposed that "Everyone designs who devises courses of action aimed at changing existing situations into preferred ones".