Prototyping 2: What is a prototype

In my last post I discussed what a prototype does. Now here comes a far trickier question: what is a prototype. A prototype turns out to be quite complex, and rightly so. Because to get the benefits of prototyping (the subject of my next post), a prototyper must understand these vital concepts, otherwise you are just shooting arrow into the air.

A prototype is deservedly complex since it is by definition the coming together of many different disciplines. Whether you like it or not every prototype has an either implied or explicit:

  • visual design
  • interaction design
  • technical implementation
  • information design
  • editorial content
  • and my personal favorite: a reason to exist

But those are all vague terms and do not really help you get control of your prototype. And getting control is the point of the definition of a prototype that I want to discuss. This definition will provide you with everything you need to control your prototype, so it does not control you. Likewise, for you non-prototypers, this will also give you enough information to fight what I call the razzle-dazzle effect: a prototyper who over-delivers a slick prototype and uses the wow factor to cover up a paucity of good ideas.

To begin, we need a prototype definition that covers what are the parts that make up a prototype and not what a prototype does (that was covered in the last post).

The Effective Prototyping definition of a prototype

A prototype is a model of a design that is:

  • utilized for a specific planned purpose
  • illustrating specific content and fidelity
  • articulating defined requirements and assumption
  • specified with prototyping characteristics
  • customized for a specific audience(s)
  • created with a specific tool
  • performed in a specific method

Here is a less verbose but more specific version of the same definition:

A prototype is a model of a design with:

  • purpose
  • content
  • content fidelity
  • requirements and assumption
  • prototyping characteristics
  • defined audience (s)
  • toolset
  • method

Below we will discuss them briefly, for more thorough details, you can always consult the full book, Effective Prototyping for Software Makers .


A prototype will be created for a specific purpose. Whether it is a proof of concept, or a demonstration of a product’s interaction or a visual direction, it is important to know what the purpose(s) is (are).


Based on what the purpose of the prototype is, you will want to prioritize the content in the prototype.

A prototype consists chiefly of 4 different types of content:

  • Interaction — how a user will interact with it
  • Visual design — how the prototype will visually appear
  • Editorial content — what information will be on the prototype
  • Information Design/Architecture — what will be the structure of the information


Generally, only in late stages do you want the content all at a high fidelity. Consequently, a prototyper will strategically set the fidelity of any given content higher or lower depending on what they want the prototype to focus on. The higher the fidelity, the more prominent the content. The lower the fidelity, the more the content will fade into the background.

Setting the wrong level of fidelity is the most common error. It results in discussions getting bogged down on visual design, when in fact the interaction design was the only intended goal of the prototype.

Contrary to what most prototyping texts state you can play with fidelity within a content type. For example you can raise the fidelity on the visual design for the chrome of an application and lower the fidelity of the content in order to discuss the visual structure of a given. You can also de-emphasize a content type completely, for example by showing all text in greeked text format you for your audience to concentrate on the visuals or interactions instead of trying to read editorial content which usually grabs their attention.

However, the issue is more nuanced than it appears. For example, let’s say you want to test the interaction design. Then, if you set the visual design level to lowest and editorial content to lowest fidelity, it will be impossible to really test the interaction: you need just enough editorial and visual design content to test the interaction. Likewise, say for example, the visual design is already finished and agreed on by stakeholders, then there is no real reason not to use a high fidelity visual design.

In general, the rule is, lower the fidelity of the content you are both less sure of and do not want to evaluate. At any rate a professional prototyper should be able to justify their choices.

requirements and assumption

The whole point of a prototype, when used as part of a digital product or service creation process is to validate requirements, or rather separate the requirements from the assumptions. Requirements are some function or feature that is necessary for the success of the product or service. An assumption is something that is presupposed to be a requirement, but has never actually been proven or tested. A prototype usually consists of proven requirements, requirements to be validated in the current iteration and assumptions. In general, the higher the assumptions the more risky a prototype is. Whether something is a requirement or an assumption will help prioritize content and set its fidelity.

I see know the post is over 1,000 words, so let’s stop here and resume with prototyping characteristics next week.

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