--- title: "Usability" url: "https://insideuxdesign.com/en/glossar/usability" language: "en" description: "What does usability mean? A plain-language explanation with the ISO definition, an example and practical tips. Learn how to spot good usability." published: "2026-10-14T15:19:21+02:00" updated: "2026-10-14T15:19:21+02:00" --- # Usability Usability describes how well people can use a product to reach their goal: effectively, without unnecessary effort and with a good feeling. - **Buchstabe:** U - **Englischer Begriff:** Usability 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?](https://insideuxdesign.com/en/blog/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](https://insideuxdesign.com/en/glossar/usability-testing) reveals problems the team no longer notices. - **Check with expert knowledge first.** A [heuristic evaluation](https://insideuxdesign.com/en/glossar/heuristic-evaluation) finds obvious weaknesses quickly and cheaply. - **Measure whether it improves.** Metrics like success rate, time on task or the [System Usability Scale](https://insideuxdesign.com/en/glossar/system-usability-scale) make progress visible. Common pitfalls are collected in [Common Usability Mistakes and How to Avoid Them](https://insideuxdesign.com/en/blog/common-usability-mistakes-and-how-to-avoid-them). ## Related terms [Usability Testing](https://insideuxdesign.com/en/glossar/usability-testing), [Heuristic Evaluation](https://insideuxdesign.com/en/glossar/heuristic-evaluation), [System Usability Scale](https://insideuxdesign.com/en/glossar/system-usability-scale), [Cognitive Load](https://insideuxdesign.com/en/glossar/cognitive-load) ## Sources - [ISO: ISO 9241-11:2018, Ergonomics of human-system interaction, Part 11: Usability: Definitions and concepts. ISO, 2018](https://www.iso.org/standard/63500.html) - [Jakob Nielsen: Usability 101: Introduction to Usability. Nielsen Norman Group, 2012](https://www.nngroup.com/articles/usability-101-introduction-to-usability/) ## More terms [ ### A/B Testing An A/B test is an experiment that shows two versions of a page or element at the same time to randomly split groups of visitors. It lets you decide with real data which version works better. ](https://insideuxdesign.com/en/glossar/a-b-testing) [ ### ARIA ARIA is a W3C standard that adds roles, states and properties to HTML. It tells screen readers what an element is and how it currently behaves. ](https://insideuxdesign.com/en/glossar/aria) [ ### Accessibility Accessibility means designing websites, apps and digital documents so that everyone can use them, including people with visual, hearing, motor or cognitive disabilities. ](https://insideuxdesign.com/en/glossar/accessibility) [ ### Affordance An affordance describes what action an object makes possible and whether people can recognize it: a button invites you to press it, a handle invites you to pull. ](https://insideuxdesign.com/en/glossar/affordance) [ ### Alt Text Alt text is a short text version of an image, stored in the HTML alt attribute. Screen readers read it aloud so people who can’t see the image get the same information. ](https://insideuxdesign.com/en/glossar/alt-text) [ ### Atomic Design Atomic Design is a method for building user interfaces from small, reusable building blocks, from single elements like buttons all the way up to complete pages. ](https://insideuxdesign.com/en/glossar/atomic-design) [ ### BFSG The BFSG, Germany’s Accessibility Strengthening Act, has required many companies since 28 June 2025 to make certain products and digital services, such as online shops, accessible. ](https://insideuxdesign.com/en/glossar/bfsg) [ ### Card Sorting Card sorting is a research method in which people sort terms written on cards into groups. It shows you how they mentally organize content, so you can plan navigation that makes sense to them. ](https://insideuxdesign.com/en/glossar/card-sorting) [ ### Cognitive Load Cognitive load is the mental effort it takes to understand and use an interface. The less unnecessary thinking a design demands, the easier the actual task becomes. ](https://insideuxdesign.com/en/glossar/cognitive-load) [ ### Color Vision Deficiency A color vision deficiency means someone has a harder time telling certain colors apart than most people. The most common type is red-green deficiency. ](https://insideuxdesign.com/en/glossar/color-vision-deficiency) [ ### Contextual Inquiry Contextual inquiry is a research method where you observe and interview people in their real work environment. It shows you how they actually get tasks done, not just how they describe it. ](https://insideuxdesign.com/en/glossar/contextual-inquiry) [ ### Contrast Ratio The contrast ratio describes how much two colors differ in brightness, such as text and background. WCAG requires at least 4.5:1 for normal text. ](https://insideuxdesign.com/en/glossar/contrast-ratio)