Personas are a descriptive explanation of the primary user in terms of their specific behavior patterns, or why they do what they do, where they do it and how.  This primary user -- a specific, complete (if fictional) individual who must be satisfied with the product in order to consider it a success -- rallies the design team around A User, not Any User.  The impact of having a shared view on the user means that functionality can be parsed based on how much it supports that primary user's reasons for acting and responding in specific ways.

Method

Personas are an elegant description of user goals (like their definition of success, preferred ways of relating, ultimate intent of efforts) based on user research.  Gaps in user research get filled with market research, literature and from subject-matter experts.  Synthesizing the characteristics and relevant goals of the primary and secondary users must be accomplished before composing the narrative that will reflect the end-user for the design team.  Often a photograph accompanies the prose to increase the visceral realism of the persona for the team.

Results

Design teams benefit most from primary personas.  Where there is a wider audience of potential users, teams can construct secondary personas (he who supports the primary) and supplemental personas (those whose needs are served in a managerial or political capacity through the product). 

This persona explains the state of mind and needs of a Medical Administrative Secretary:

Sheila is the administrative support person for 25 people, 5 of whom are located in other buildings. She works entirely from her desk, using her phone to contact other secretaries and find suppliers. To support her workflow, she compiled in a Word document all her common references on the intranet and Internet, saved it as an html file, and made it her homepage. This provides her with quick access to the resources needed to accomplish the majority of her support responsibilities: scheduling people, ordering items, equipment and space; filling out forms; and, finding people, places and things (like auditorium lost and found, keycards or lightbulbs).

 

The greatest source of complexity for Sheila is managing the many details that have to come together neatly for each scheduling task. Tracking all the different requests from her staff runs a close second in terms of sources of stress. Her computer has value to the extent that it helps her manage the details, anticipate her next steps, and make new information quickly retrievable and actionable.

Timeframe

The persona(s) can be drafted and edited in two weeks, given the necessary collaboration and discussion with the team.

Sometimes larger issues get raised in the course of defining the primary user to solve scope and strategy issues as well.  The process of constructing a persona can often provoke questions of "who is our audience really?" and "what stereotypes affect how we see our customer base?"  These answers benefit not only a design team but also the sales and marketing divisions of a company.

Preparation

Personas are based on user research collected using methods like Delphi, Contextual Inquiries and/or On-site Observations. 

Additional Reading

Alan Cooper of Cooper Interaction Design created this technique to help distinguish wants from needs from requirements in defining and selecting product features.  Cooper's text is an essential reference for this technique.

About Face 2.0: The Essentials of Interaction Design, Alan Cooper and Robert Reimann (2003) Wiley Publishing. See Chapter 5 especially.

Kim Goodwin works with Alan Cooper and has written a helpful, brief article at: http://www.cooper.com/newsletters/2001_07/perfecting_your_personas.htm