User experience

User experience (UX) refers to a person's emotions and attitudes about using a particular product, system or service. It includes the practical, experiential, affective, meaningful and valuable aspects of human–computer interaction and product ownership. Additionally, it includes a person’s perceptions of system aspects such as utility, ease of use and efficiency. User experience may be considered subjective in nature to the degree that it is about individual perception and thought with respect to the system. User experience is dynamic as it is constantly modified over time due to changing usage circumstances and changes to individual systems as well as the wider usage context in which they can be found.

The international standard on ergonomics of human system interaction, ISO 9241-210, defines user experience as "a person's perceptions and responses that result from the use or anticipated use of a product, system or service". According to the ISO definition, user experience includes all the users' emotions, beliefs, preferences, perceptions, physical and psychological responses, behaviors and accomplishments that occur before, during and after use. The ISO also list three factors that influence user experience: system, user and the context of use.

Note 3 of the standard hints that usability addresses aspects of user experience, e.g. "usability criteria can be used to assess aspects of user experience". The standard does not go further in clarifying the relation between user experience and usability. Clearly, the two are overlapping concepts, with usability including pragmatic aspects (getting a task done) and user experience focusing on users’ feelings stemming both from pragmatic and hedonic aspects of the system. Many practitioners use the terms interchangeably. The term usability pre-dates the term user experience. Part of the reason the terms are often used interchangeably is that, as a practical matter, a user will at minimum require sufficient usability to accomplish a task, while the feelings of the user may be less important, even to the user herself. Since usability is about getting a task done, aspects of user experience like information architecture and user interface can help or hinder a user's experience. If a website has "bad" information architecture and a user has a difficult time finding what they are looking for, then a user will not have an effective, efficient and satisfying search.

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