Design prototyping in its broader definition comprises the actions to make, test and analyse a prototype, a model or a mockup according to one or various purposes in different stages ^[1] of the design process.^[2][3] Other definitions consider prototyping as the methods or techniques for making a prototype (e.g., rapid prototyping techniques),^[4] or a stage in the design process (prototype development, prototype or prototyping).^[5][6][3][7] The concept of prototyping in design disciplines' literature is also related to the concepts of experimentation (i.e., an iterative problem-solving process of trying, failing and improving),^[4] and Research through Design (RtD) (i.e., designers make a prototype with the purpose of conducting research and generating knowledge while trying it, rather than aiming to improving it to become a final product).^[8][9]

Initial references to the concept of prototyping in design could be traced to the proceedings of the Conference on Design Methods ^[10] in 1962:

"As you come down in scale, it is much more likely that you will be able to mass produce the object, and therefore be able to make a prototype, test it and try it out and explore it."

— J.K. Page ^[11]

In 1968, Bruce Archer, a relevant figure in the "Design Methods Movement" describes the design process. One of the stages of the process is called "Prototype development" and it indicates activities to build and test a prototype.^[12] Thus, it would be possible to say that from a design methods' perspective, prototyping recalls a process in which a prototype is built, tried out and tested. In the same line, additional references to prototyping can be found in later editions of the Design Research Society's Conferences.^[13] For example, referring to build models and use them to consult people out of the design team, review the model and make decisions on how to modify the design proposal;^[14] or describing modelling (creating a model) and model simulation.^[15]

However, one of the first documented uses of the term prototyping linked to a design process appears in 1983 in A systematic look at prototyping ^[2] in the field of information systems and software development. The work of Floyd was inspired by the discussions among the scholars who were preparing the Working Conference on Prototyping. It focuses on prototype as a process, rather than the artefact and how prototyping could be applied to the full solution (or product) or parts of it seeking to improve the final output. Although this work was not developed within the design discipline, it provides a comprehensive characterisation of prototyping by defining its steps, purposes and strategies. Moreover, it serves as a referent to further studies of design prototyping.

Later, around the year of 1990, the availability of methods for rapidly manufacturing models and prototypes stimulated the publication of a great body of literature dedicated to rapid prototyping techniques and technologies (e.g., 3D printing). Technologies for additive manufacturing (i.e., adding material) or substractive manufacturing (i.e., removing material) together with the use of software for computer-aided design (CAD), leveraged prototype building but also the fabrication of products in limited numbers.

Along the years, further efforts have been dedicated to characterising prototyping in design disciplines in the fields of interaction design, experience design,^[16] product design^[17] and service design,^[1][18][3] as well as in product-design-related fields such as engineering/mechanical design.^[19][20] In 2000, designers from IDEO described experience prototyping, introducing types of design representations and methods that allow to simulate aspects of an interaction that people experience by themselves.^[16] Experience prototyping can combine various types of prototypes such as spaces, products and interfaces to resemble what the real experience could be like. Around the year of 2010, studies were developed to examine the prototyping of services theorising from the growing practice of service design,^[18] which later in 2018 were also used as a reference for service design practitioners.^[3]

Prototyping is developed in an iterative cycle of making, testing and analysing which allows to examine dimensions of a solution before its future implementation, anticipating to possible issues and improving them earlier in the process. This cycle can be portrayed the following steps:^[2][21][3]

1. Preparation: to decide the aims of prototyping, define questions and assumptions that are going to be examined, identify the participants of the prototyping sessions and the dimensions of the prototype that are going to be tested.
2. Making: some or various dimensions will be represented in a prototype (e.g., material, form or function) ^[22] employing an appropriate^{[clarification needed]} depending on the purpose. The relevance on making on design has been increasing in the last years and transforming while new design disciplines emerge. For instance, whilst sketches were previously another category of visual design representations,^[23] today they could also be considered prototypes in service design.^[3]
3. Testing: the prototyping session develops in a defined setup with certain characteristics of space and environment and will follow a method to gather feedback.
4. Analysing: the results of the testing will be integrated into the solution and updated in the following prototype versions.

One example of this cycle could be the design of a digital interface in the early stages of the process applying paper prototyping.^[24] In this case, prototyping may seek to explore and evaluate multiple alternatives of ideas with the users as fast and cheap as possible, before investing time to program it. Thus, the prototypes will represent the structure of the interface by using simple forms and text to indicate the elements (1). A common technique for creating prototypes of digital interfaces would be to sketch wireframes in paper (2). The team will meet with a potential user and the wireframes will be presented by the design researcher. The user will simulate to click the elements and explain the actions that intends to do while moving to other sheets that represent other screens in the navigation flow (3). The feedback gathered will be used to make decisions on the aspects that need to be modified and the layout of the interface will be updated (4).

To prepare for prototyping, some aspects need to be decided. For this purpose, it is useful to individualise and consider various characteristics that will allow identifying how prototyping should be developed according to the design needs.^[3] In this regard, the prototyping framework proposed by Blomkvist and Holmid could provide some guidelines.^[1] As a result of a literature review, they identify a set of characteristics which are:

• Prototype
• Model
• Mockup
• Rapid prototyping
• Design methods
• Interaction design
• User experience design
• Product design
• Service design
• Participatory design - co-design