A designer must consider the end user's needs, wants and limitations within every element of the design cycle. The ability to identify how users will interact with a product, service or system is vital for its success. To achieve this, designers must be able to acquire and analyse valid data without making assumptions about how the product may be used. The ability to put aside one’s own ideas and biases is essential for UCD. Designers must act with integrity and not project their own ideas of what the user requirements are when trying to create technological solutions to their problems

User-Centred Design (UCD) is a design process that pays particular attention to the needs of potential product users through the involvement of users at all stages of the design process. It considers how users are likely to use the product and tests products with actual users. Sometimes called “empathic design”, the user-centred approach puts the design team in direct contact with the people they are designing for, that is, to empathize with potential users and gain a better understanding of their thoughts, needs, values and beliefs. The design team often includes anthropologists, ethnographers and psychologists to advise the creative designers.

When following a UCD approach to the design process:

• A design is based on an explicit understanding of users, tasks and environments.

• Users are involved throughout design and development.

• The design is driven and refined by user-centred evaluation.

• The process is iterative.

• The design addresses the whole user experience.

• The design team includes multidisciplinary skills and perspectives.

In UCD the concept of 'user' is broad. A user is anyone who interacts with a design or is directly or indirectly affected by its function. The purpose of user group studies is to identify the needs of all who interact with the product at different stages. User groups could be:

• End users - the person who will buy and use the product.

• Co-users - people affected by the use of the product, without being a direct end-user.

• Maintenance workers - people who maintain or fix products when they break.

• End-of-life users - people who are involved with dealing with the product when it is no longer useful - recyclers, disassembly etc.

User group studies focus on users, their activities, and their social and cultural context. Most often the studies use a combination of qualitative and quantitative approaches. They are either looking to physically measure something, or gather users' feelings from interacting with the product.

The purpose of user groups is to gather measurable, usable and actionable feedback on a design. Ideally the real product is tested in its normal environment but a mock-up or controlled environment can be used. 

UCD Proposes the use of multidisciplinary design teams. This is because, as stated before, UCDn requires an explicit understanding of the user, task and environment of a product or system. Designers must understand the full context of use. This can mean involving the following disciplines:

• Anthropologists treat human society as a field of science and want to know why things happen. They tackle big human problems, such as overpopulation, warfare and poverty. Anthropology considers how people’s behaviours change over time, and how people in seemingly dissimilar compare and contrast.

• Ethnographers have direct interaction with people to collect and record data about human culture and societies. There are various methods ethnographers employ to study different sub-cultures of society. They often need to find patterns in and understand issues facing a wide sample of people with diverse backgrounds.

• Psychologists specialize in the study of mind and behaviour or in the treatment of mental, emotional, and behavioural disorders. They are concerned with how and why people do certain things and behave in certain ways.

UCD focuses on better mainstream solutions for everyone rather than providing different solutions for different user groups ('special needs design'). Inclusive design ensures there that there is a sufficient market for a product and increases its feasibility as an innovation.

Demographic change is a major challenge for designers. There are already over 130 million people over 50 in the EU alone. This means that one in every two adults will be over that age. The rapid ageing populations and growing numbers of people with disability are having a profound effect on new product and service design. Designs that include the needs of marginalised groups of people is regarded not only as socially desirable but also as a commercial opportunity. If you design products for people with no difficulties, you are then excluding a large portion of the population. It makes no commercial sense to do so.

Inclusive design requires designing universally acceptable products, including those with physical, sensory, cognitive and other challenges and impairments.