UX glossary · engl. Usability
Usability
Usability describes how well people can use a product to reach their goal: effectively, without unnecessary effort and with a good feeling.
Imagine you want to buy a ticket at a train station in a hurry. The machine shows ten fare options with abbreviations you don’t know, the back button resets everything, and in the end it rejects your card. The train leaves without you. Technically, the machine works. It just isn’t usable.
That difference is what usability is all about.
Explained simply
Usability describes how easy a product is to use. Think of two can openers: both can open a can. With one, it takes seconds. With the other, you need three attempts and nearly cut yourself. Both work, but only one is usable.
The standard ISO 9241-11 defines usability, in essence, like this: specific people can use a product in a specific context of use to reach specific goals with effectiveness, efficiency and satisfaction. Effective means the goal is reached at all. Efficient means without unnecessary effort. Satisfying means using it doesn’t feel like a fight.
How to recognize good usability
Jakob Nielsen describes five quality components that make a helpful checklist:
- Learnability: How quickly do people find their way on first contact?
- Efficiency: How fast can they work once they know the product?
- Memorability: Can they pick it up again after a break?
- Errors: How often do mistakes happen, how serious are they, and how easy is it to recover?
- Satisfaction: How pleasant is it to use?
The word “specific” in the definition matters. Usability isn’t a fixed property of a product. It depends on who uses it in which situation. Professional video editing software can be more complex than an app for sharing photos.
Usability is also part of the broader user experience, which covers the entire experience with an offering, including expectations, feelings and everything that happens before and after use. You can read more in What Is Usability?.
An example
Here’s an example: an online shop asks for your date of birth in a free text field at checkout. Some people type “1/4/88”, others “01/04/1988”, and many get an error message that only says “Invalid input.” Some of them give up.
After the redesign, the field shows a sample format, accepts different spellings and explains what it expects when something goes wrong. The task is the same. Only the usability has improved.
In practice
- Test with real people. A small round of usability testing reveals problems the team no longer notices.
- Check with expert knowledge first. A heuristic evaluation finds obvious weaknesses quickly and cheaply.
- Measure whether it improves. Metrics like success rate, time on task or the System Usability Scale make progress visible. Common pitfalls are collected in Common Usability Mistakes and How to Avoid Them.
Related terms
Usability Testing, Heuristic Evaluation, System Usability Scale, Cognitive Load