What constitutes usability: users, tasks and context of use
Usability is the extent to which specific users can achieve specific goals effectively, efficiently and with satisfaction in a specific context of use. Understanding that context, including the users, their tasks, their equipment and their physical, social and organisational environment, is what allows teams to design products that work in real conditions rather than only in ideal ones.
Usability defined
The international standard ISO 9241-11 defines usability as 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. The definition is short, but every part of it matters. Effectiveness asks whether people can complete their goals accurately. Efficiency asks how much effort, time or resources it takes. Satisfaction asks how people feel about the experience.
The phrase that is easiest to overlook is "in a specified context of use". It means that usability is never a fixed property of a design. A product can be very usable for one group of people in one situation and difficult for another group in a different situation. Our posts on designing for usability and why usability matters across sectors cover the principles and stakes; this guide focuses on context.
The elements of context of use
| Element | Questions to ask | Example |
|---|---|---|
| Users | Who are they? What skills, experience, abilities and languages do they have? | New customers, expert operators, older users |
| Goals and tasks | What are they trying to achieve? How often? How complex? | Booking an appointment, approving an invoice |
| Equipment | What devices, screens, inputs and connections do they use? | Old Android phone, shared desktop, tablet with gloves |
| Physical environment | Where are they? Light, noise, movement, temperature? | Bright sunlight, noisy factory, moving vehicle |
| Social and organisational | Who else is involved? What pressures, rules or interruptions exist? | Busy reception desk, compliance checks, shift work |
How context changes usability
Consider a mobile app for recording equipment inspections. In an office, on a large screen with a stable connection, it might work perfectly. On an outdoor site, the same app may be hard to read in bright sunlight, difficult to operate with gloves, slow on a weak connection and constantly interrupted by colleagues or safety alerts. The design has not changed, but its usability has.
- Hospital ward: Time pressure, interruptions and safety-critical decisions demand clear alerts and error prevention.
- Retail checkout: Speed and simplicity matter most; customers may be distracted or in a queue.
- Government service: Users vary widely in digital confidence, language and ability.
- Field work: Outdoor light, gloves and poor connectivity shape every design choice.
Context in Gulf markets
Products used in the UAE and Saudi Arabia often face particular contextual factors. Strong sunlight affects screen readability outdoors, users switch between Arabic and English, many people rely primarily on mobile phones, and audiences include a wide mix of nationalities, ages and levels of digital confidence. Seasonal patterns, such as changed working hours during Ramadan, can also shift when and how people use services. Designing with these factors in mind makes products more usable for the people who actually rely on them.
Analysing context of use
Context analysis should happen early, before detailed design begins. It combines several research methods: interviews to understand goals and constraints, observation in the real environment, surveys to understand the range of users and devices, and analytics to see how existing products are used. The output is a clear description of the main user groups, their key tasks and the conditions they work in.
- Identify user groups: List the main types of users and their characteristics.
- List key tasks: Describe the most important and frequent tasks for each group.
- Observe the environment: Visit or record where and how people actually work.
- Document equipment: Capture devices, screen sizes, inputs and connectivity.
- Note social factors: Record interruptions, pressures, rules and collaboration.
- Share and use: Turn findings into design requirements and test scenarios.
Designing for real contexts
- Use high contrast and large text where lighting or vision varies
- Provide large touch targets for gloves, movement or limited dexterity
- Support offline use or poor connectivity where needed
- Design for interruptions, saving progress automatically
- Offer multiple languages and plain wording for diverse users
- Reduce steps for time-pressured tasks
Testing in realistic conditions
Usability tests in a quiet meeting room can miss problems that appear in real conditions. Where possible, test where the product will be used, with realistic devices and interruptions, or recreate key conditions such as bright light, noise or slow connections. Our guide to user research methods describes contextual inquiry and diary studies, which are particularly useful for understanding real use.
Measuring usability in context
Usability metrics such as task success, time on task, error rate and satisfaction scores are most meaningful when they are measured for specific user groups and tasks in realistic conditions. Comparing results across contexts, such as office versus field use, often reveals where design improvements will have the biggest effect. Our post on measuring user experience explains how to choose and track these measures.
Frequently asked questions
What is context of use?
The users, their goals and tasks, their equipment and their physical, social and organisational environment, which together shape how usable a product is.
Why does context matter for usability?
The same design can be easy in one setting and difficult in another, so designing without understanding context leads to products that fail in real use.
How do you analyse context of use?
Through interviews, observation in real environments, surveys, analytics and documenting devices and conditions.
Is usability the same as accessibility?
They overlap. Accessibility ensures people with disabilities can use a product; usability considers all users, tasks and contexts.
Can one design work across many contexts?
Often, with adaptations such as responsive layouts, adjustable text size, offline support and multiple languages. Research shows where adaptations are needed.