Personas are a tool for sharing our understanding of our expected users, as a starting point for design.
Nielsen (2013) notes:
The persona method has developed from being a method for IT system development to being used in many other contexts, including development of products, marketing, planning of communication, and service design. [..] Common understanding is that the persona is a description of a fictitious person, but whether this description is based on assumptions or data is not clear, and opinions also differ on what the persona description should cover.
Whenever I hear the phrase “the user,” it sounds to me like “the elastic user.” The elastic user must bend and stretch and adapt to the needs of the moment. However, our goal is to design software that will bend and stretch and adapt to the user’s needs. […] Designing for the elastic user gives the developer license to code as he pleases while paying lip service to “the user.” Real users are not elastic.[…]
In our design process, we never refer to “the user.” Instead, we refer to a very specific individual: a persona.
In the design process, we begin to imagine how the product is to work and look before any sketch is made or any features described. If the design team members have a number of persona descriptions in front of them while designing, the personas will help them maintain the perspective of the users. The moment the designers begin to imagine how a possible product is to be used by a persona, ideas will emerge. Thus, I maintain that the actual purpose of the method is not the persona descriptions, but the ability to imagine the product. In the following, I designate these product ideas as scenarios. It is in scenarios that you can imagine how the product is going to work and be used, in what context it will be used, and the specific construction of the product. And it is during the work with developing scenarios that the product ideas emerge and are described. The persona descriptions are thus a means to develop specific and precise descriptions of products.
Cooper provides some guidelines for authoring personas:
Be Specific: The more specific we make our personas, the more effective they are as design tools. That’s because personas lose elasticity as they become specific. For example, we […] don’t just let Emilee drive to work. We give her a dark-blue 1991 Toyota Camry, with a gray plastic kid’s seat strapped into the back and an ugly scrape on the rear bumper. This distinctive specificity is very powerful as a design and communications tool. Consequently, all of our personas are articulated with singular detail and precision. As we isolate Emilee with specific, idiosyncratic detail, a remarkable thing happens: She becomes a real person in the minds of the designers and programmers. […]
Giving the persona a name is one of the most important parts of successfully defining one. A persona without a name is simply not useful. Without a name, a persona will never be a concrete individual in anyone’s mind. […]
To make each persona more real to everyone involved in the product creation, I like to put faces to the names and give each persona an image. […]
Precision, Not Accuracy As a design tool, it is more important that a persona be precise than accurate. That is, it is more important to define the persona in great and specific detail than that the persona be the precisely correct one. This truth is surprising because it is the antithesis of the goal of interaction design, in which accuracy is always more important than precision. […]
Personas are the single most powerful design tool that we use. They are the foundation for all subsequent Goal-Directed design. Personas allow us to see the scope and nature of the design problem. They make it clear exactly what the user’s goals are, so we can see what the product must do – and can get away with not doing.
Cooper, A. (1999), The Inmates are Running the Asylum – Why High-Tech Products Drive Us Crazy and How to Restore the Sanity, SAMS publishing
Nielsen, L. (2013), Personas , The Interaction Design Foundation , Aarhus, Denmark. http://www.interaction-design.org/encyclopedia/personas.html