User centered design

User-centered design (UCD) or user-driven development (UDD) is a framework of processes (not restricted to interfaces or technologies) in which usability goals, user characteristics, environment, tasks and workflow of a product, service or process are given extensive attention at each stage of the design process. User-centered design can be characterized as a multi-stage problem-solving process that not only requires designers to analyze and envision the way users are likely to consume a product, but also to validate their assumptions with regard to the user behavior in real world tests. These tests are conducted with/without actual users during each stage of the process from requirements, pre-production models and post production, completing a circle of proof back to and ensuring that "development proceeds with the user as the center of focus." Such testing is necessary as it is often very difficult for the designers of a product to understand intuitively what a first-time user of their design experiences, and what each user's learning curve may look like.

The chief difference from other product design philosophies is that user-centered design tries to optimize the product around how users can, want, or need to use the product, rather than forcing the users to change their behavior to accommodate the product. The users thus stand in the center of two concentric circles. The inner circle includes the context of the product, objectives of developing it and the environment it would run in. The outer circle involves more granular details of task detail, task organization, and task flow.

The term user-centered design was coined in Donald A. Norman's research laboratory in University of California, San Diego. The concept became widely popular after the publication of the book "User-Centered System Design: New Perspectives on Human-Computer Interaction" in 1986. The concept gained further attention and acceptance in his seminal book "The Design of Everyday Things" (originally called "The Psychology of Everyday Things"). In the book, Don Norman describes the psychology behind what he deems 'good' and 'bad' design through examples. He exalts the importance of design in our everyday lives, and the consequences of errors caused by bad designs. The books also include principles of building well-designed products. His recommendations are based on the needs of the user, leaving aside what he considers secondary issues like aesthetics. The main highlights of these are:

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