A/B testing: A technique used to compare two alternative designs of a live interactive system with a large number of users.

Accessibility: The usability of a product, service, environment or facility by people with the widest range of capabilities (ISO 9241-171).

Accuracy: The extent to which an actual outcome matches an intended outcome (ISO 9241-11).

Affinity diagram: A method used by design teams to organise large amounts of qualitative research data and information into groups so that the data can be analysed.

Affordance: The properties of an object that suggest to people how the object can be interacted with; the kind of interaction that is so suggested. Compare signifier.

Alignment: The placing of graphical user interface elements so that they share horizontal or vertical coordinates.

Assumption persona: A persona developed without user research.

Boomerang technique: Answering a question with another question.

Card sort: A research method where participants organise features, functions or pages of a user interface into groups that make sense to the participants.

Closed card sort: A card sort where the categories into which information can be sorted have been predefined.

Closed question: A question where the participant must choose an answer from among a proposed list of responses. No answer other than the ones proposed is allowed.

Completeness: The extent to which users are able to achieve all intended outcomes (ISO 9241-11).

Conceptual model: A model representing the system structure and logical architecture envisaged by the designer of an interactive system.

Context of use: The users, goals and tasks, resources, and the technical, physical, social, cultural and organisational environments in which a product is used.

Contextual inquiry: A research method where a researcher carries out a site visit to observe users carrying out their normal activities in their natural environment.

Contrast: A visual design technique where the object of attention is made very different from the other elements that surround it.

Design pattern: A re-usable solution to a commonly occurring design problem.

Diary study: A longitudinal research method where users keep track of the activities in which they engage.

Discount usability: An approach to usability that seeks to optimise usability methods for cost-effectiveness.

Effectiveness: The accuracy and completeness with which users achieve specified goals. Compare efficiency (ISO 9241-11).

Efficiency: The resources used in relation to the results achieved (ISO 9241-11).

Empathy map: A visual summary of what the user hears, sees, thinks and feels within the context of use.

Ethnography: The scientific description of people and cultures with their customs, habits and mutual differences.

Eye tracking: A technique used to measure either the point of gaze (where the user is looking) or the motion of the user’s eye relative to the head.

Fidelity: When used to refer to a prototype, this refers to the degree of exactness with which the prototype reproduces the final design. Note that a prototype can have high visual fidelity but low interactive fidelity (for example, static screens created in a graphics program), and low visual fidelity but high interactive fidelity (for example, a paper prototype).

Fitts’ law: The time taken to move to a target is a function of the target size and the distance to the target.

Fixation: The pause of an eye movement on a specific area of the visual field.

Formative usability test: A type of iterative usability testing that aims to find problems with a system so they can be fixed.

Functional properties: Inherent properties of a software product that determine what the software is able to do: generally concerned with transformation of input data to output data (ISO/IEC 25010).

Functional requirement: A requirement specifying functional properties of a system.

Gaze plot: A moment-by-moment representation of a user’s eye movement across the screen.

Goal: An intended outcome (ISO 9241-11).

Heat map: A representation of the different areas of the screen where the user has spent the most time looking.

Heuristic: A guideline for evaluating the usability of a user interface.

Hick’s law: The time taken to make a decision increases as the number of choices is expanded.

High-fidelity prototype: A prototype that appears very similar to the final system.

Implementation model: The view of the system from the developers’ point of view, often with system models and so on.

Indirect user: A person who receives output from a system, but does not interact with the system (ISO/IEC 25010).

Information architecture: The discipline that ensures users can find the functions, features or content they need to achieve their tasks.

Interaction design: The practice of identifying design solutions and creating prototype user interfaces.

Interactive system: A combination of hardware and/or software and/or services and/or people that users interact with in order to achieve specific goals (ISO 9241-11).

Interface control: An element of interaction in a graphical user interface, such as a button or scroll bar.

Interface pattern: See design pattern.

Iterative design: A design method based on a cyclical process of prototyping, testing, analysing and refining a system. Based on the results of testing the most recent iteration of a design, changes and refinements are made.

Leading question: An interview question phrased in such a way that it tends to suggest the desired answer.

Longitudinal research: Research that collects data from the same individual(s) over an extended period of time.

Low-fidelity prototype: A prototype that has some characteristics of the target system but is otherwise simple, usually in order to produce the prototype and test broad concepts quickly.

Mental model: The internal, mental representation that a user has about how an interactive system works.

Microcopy: Text labels that appear on buttons, dialog names, form fields and tooltips.

Moderated usability test: A usability test where a test administrator is with a test participant in real time (whether physically present or not), for example, to remind the participant to think aloud.

Moderator: The person who runs a usability test. The moderator is responsible for ensuring the smooth running of the session and for ensuring that the test objectives are addressed.

Monothetic agglomerative cluster analysis: A statistical method of analysing results of a card sorting session.

Multivariate testing: Generalised version of A/B testing, where there are more than two alternatives.

Negative persona: A persona representing users whom the service is specifically not designed to serve.

Non-functional requirement: A requirement specifying properties of a system that are not functional properties.

Observation: In the context of a usability test, this is something the participant says or does (as distinguished from an ‘interpretation’, which is the observer’s belief about the cause).

Open card sort: A card sort where users can create their own grouping scheme.

Open question: A question that cannot be answered ‘Yes’ or ‘No’ but requires the participant to answer with a sentence or two.

Paper prototype: A prototyping technique that involves creating drawings (often roughly drawn) of a user interface that can be used to test out design ideas with end users. There is often the ability to ‘interact’ with the prototype.

Persona: A fictitious person created to model and describe the goals, needs and characteristics of a specific type or group of users.

Primary persona: The main target for the design of the service.

Primary user: A person who interacts with the product (ISO 25010).

Progressive disclosure: An interaction design technique that helps to maintain the focus of a user’s attention by reducing clutter, confusion and cognitive workload. This improves usability by presenting only the minimum information required for the task at hand.

Prototype: Representation of all or part of an interactive system that, although limited in some way, can be used for analysis, design and evaluation (ISO 9241-210); to create and use such representations.

Proximity: A visual design technique used to organise and group the various parts of a user interface.

Qualitative research: Analysis of motivations, patterns of thought, opinion, attitude, assessment or behaviour (ISO 20252).

Quantitative research: The numerical representation of observations for the purpose of describing and explaining phenomena that those observations reflect (ISO 20252).

Recall question: A question that requires the participant to remember an event that has happened in the past.

Repetition: A visual design technique used to create consistency and to add visual interest.

Requirement: (1) A condition or capability needed by a user to solve a problem or achieve an objective. (2) A condition or capability that must be met or possessed by a system or system component to satisfy a contract, standard, specification or other formally imposed documents. (3) A documented representation of a condition or capability as in (1) or (2) (IEEE 610.12-1990).

Saccade: The movement of the eye from one part of the visual field to another.

Sample size: The number of participants interviewed or observed and so on in a given research study.

Satisfaction: The extent to which the user’s physical, cognitive and emotional responses that result from the use of a system, product or service meet the user’s needs and expectations (ISO 9241-11).

Scrum: A product development framework, falling within the ‘Agile’ set of methods. Attributed to Ken Schwaber.

Signifier: An indicator of how something is designed to be interacted with to get an intended result. Compare affordance.

Sketch: A design concept or solution not intended for testing with users.

Stakeholder: An individual or organisation having a right, share, claim or interest in a system or in its possession of characteristics that meet their needs and expectations (ISO 15288).

Summative usability test: A type of usability testing that aims to measure usability metrics, such as effectiveness, efficiency and satisfaction.

System: A combination of interacting elements organised to achieve one or more stated purposes (ISO 25010).

Task: Physical or cognitive activities required to achieve a goal (ISO 9241-11).

Thinking aloud: A technique from cognitive interviewing where a participant describes his or her thought processes when engaged in an activity.

Unmoderated usability test: A usability test where the test participant works alone on the test tasks, for example, from their home computer.

Usability: The extent to which a system, product or service can be used by specified users to achieve specified goals with effectiveness, efficiency and satisfaction in a specified context of use (ISO 9241-11).

Usability inspection: A usability evaluation process where an expert evaluates a design against a set of usability principles or standards.

User: Person who interacts with a product (or system or service) (ISO 9241-11); individual or group that interacts with a system or benefits from a system during its utilisation (ISO 25010).

User acceptance test: A test conducted to determine if the functional requirements of a specification have been met.

User-centred design: A design process in which the needs, wants and limitations of the end users of a product, service or process are considered at each stage of design.

User experience: A person’s perceptions and responses resulting from the use or anticipated use of a product, system or service (ISO 9241-210).

User group: A subset of intended users who are differentiated from other intended users by characteristics of the users, tasks or environments that could influence usability (ISO 9241-11).

User interface: All components of an interactive system that provide information and controls for the user to accomplish specific tasks with the interactive system (ISO 9241-110).

User journey map: A diagram showing the steps in a scenario in which a user interacts with a system or service.

User need: In UK government terminology, a user objective expressed in user story format.

User research: The process of uncovering user needs, goals and motivations.

User story: User stories are part of an agile approach that helps to shift the focus from writing about requirements to talking about them. All Agile user stories include a written sentence or two and, more importantly, a series of conversations about desired functionality. The most common general format is ‘As a [user role] I need/want to [do this task] so that [I can achieve this goal].’

Validated learning: A form of iterative design where the design team test design hypotheses with users.

Visual design: The practice of devising grids, laying out pages, choosing colour palettes and developing icons.

Wireframe: An image, or set of images, which displays the functional elements of a website or page, typically used for planning a site’s structure and functionality.