Discovery: Gather all marketing requirements and engineering work to-date on the project. Develop detailed user scenarios. Research the competition, identify strengths and weaknesses of current product offerings, do comprehensive and exhaustive analysis based on user scenarios.
Concepts: Describe an initial vision for the product in words. Create high-level wireframe flowcharts of user scenarios, and propose information architectures (IA) and preliminary HI for key features. Get agreement from product marketing and engineering that the IA and HI concepts meet requirements and reflect facts uncovered during discovery. Conduct user tests on high-fidelity concepts.
Design: Refine concepts on the basis of user tests. Finalize the IA and define, design, and write all interactions, dialogs, error states, menus, icons, and tips. The HI design is implemented for the alpha version of the product.
Specifications: Produce pixel-level layouts, color specs, detailed interaction descriptions, and all bitmap graphics and animations. The final HI specification is the plan of record for the end-user experience and is part of the beta version product requirements.
I introduced the first standardized HI process at Palm in 1999. I've refined the process over the past seven years to address the additional needs of other stakeholders such as engineering and product marketing.
This is an idealized design process. Business world realities (e.g. too little time, money or both) often make it impossible for any one project to go through each of the steps in as much detail as is usually desired.
But understanding and following process—whenever possible—is important. Projects go much more smoothly when team members and stakeholders can refer, as needed, to an official HI development process for ready-made and already-understood practices, procedures, deliverables and standards. This facilitates communication between team members and, perhaps most importantly, with groups outside of the core team.