What is Usability testing?
Usability testing is a research method where representative users attempt realistic tasks with a product while researchers observe, identifying problems that prevent or slow task completion.
How it works
Usability testing can be moderated (facilitator present) or unmoderated (participant works independently), in-person or remote, and formative (finding problems to fix) or summative (measuring performance). The fundamental process involves defining tasks that represent real user goals, recruiting representative participants, observing task attempts, and analyzing patterns across sessions. Nielsen’s research demonstrated that 5 users typically uncover 85% of usability problems, making usability testing surprisingly efficient. The most common finding across usability tests is not that the product is broken, but that users interpret labels, navigation, and workflows differently than designers assumed.
Applied example
Five users attempt to find and compare health insurance plans on a government website. All five struggle with the same filter interface: they cannot figure out how to apply multiple filters simultaneously because the ‘Apply’ button is below the fold. This single observation, visible to any team member watching, generates more design momentum than months of analytics.
Why it matters
Usability testing is the most consistently valuable UX research method because it replaces assumptions about user behavior with direct observation, making problems visible and undeniable to everyone who watches.
