Usability 101: Fundamentals and Definition - What, Why, How (Jakob Nielsen's Alertbox): "useit.com -> Alertbox -> Aug. 2003 Usability 101 | Search Jakob Nielsen's Alertbox, August 25, 2003: Usability 101: Introduction to Usability Summary: What is usability? How, when, and where can you improve it? Why should you care? This overview answers these basic questions. This is the article to give to your boss or anyone else who doesn't have much time, but needs to know the basic usability facts. What Usability is a quality attribute that assesses how easy user interfaces are to use. The word 'usability' also refers to methods for improving ease-of-use during the design process. Usability has five quality components: * Learnability: How easy is it for users to accomplish basic tasks the first time they encounter the design? * Efficiency: Once users have learned the design, how quickly can they perform tasks? * Memorability: When users return to the design after a period of not using it, how easily can they reestablish proficiency? * Errors: How many errors do users make, how severe are these errors, and how easily can they recover from the errors? * Satisfaction: How pleasant is it to use the design? There are many other important quality attributes. A key one is utility, which refers to the design's functionality: Does it do what users need? Usability and utility are equally important: It matters little that something is easy if it's not what you want. It's also no good if the system can hypothetically do what you want, but you can't make it happen because the user interface is too difficult. To study a design's utility, you can use the same user research methods that improve usability. Why On the Web, usability is a necessary condition for survival. If a website is difficult to use, people leave. If the homepage fails to clearly state what a company offers and what users can do on the site, people leave. If users get los"