Usability

The five components

Jakob Nielsen describes usability through five quality attributes:

• Learnability: how easy it is to do basic tasks the first time.
• Efficiency: how quickly people work once they've learned it.
• Memorability: how easy it is to come back after a period of not using it.
• Errors: how many are made, how serious they are and how easy it is to recover.
• Satisfaction: how pleasant it is to use.

How it's evaluated

• User testing: people from the target audience are asked to complete real tasks while you watch where they hesitate or fail. In 2000 Nielsen argued that five users are enough to find most problems in each round, and that several small rounds beat one big one.
• Heuristic evaluation: experts review the interface against recognized principles, such as Nielsen's ten heuristics (visibility of system status, error prevention, consistency…).
• Metrics: task success rate, time on task, errors and standardized questionnaires such as the SUS (System Usability Scale).
• Usage data: analytics, session recordings and support tickets.

Usability, UX and accessibility

• Usability focuses on whether something can be used well.
• User experience (UX) is broader: it includes perceptions, emotions and every contact with the product.
• Accessibility ensures people with disabilities can use it too. A website can be usable for most people and still not be accessible.

Common problems on B2B websites and products

• Navigation organized around the company's org chart, not around what customers are looking for.
• Long forms and unclear error messages.
• Internal terms users don't know.
• Important features hidden in menus.

Related terms

• Web accessibility (WCAG)
• Friction
• Wireframe
• Microcopy

Sources

• Nielsen Norman Group, Usability 101: Introduction to Usability.
• Nielsen Norman Group, 10 Usability Heuristics for User Interface Design.
• Nielsen Norman Group, Why You Only Need to Test with 5 Users (2000).