No. 101
User Research
Usability Testing
Usability testing is watching real people attempt tasks with a product to discover where they struggle and succeed.
Why it matters
It exposes problems designers can't see in their own work. Watching even a few users reveals issues that opinions and debates never settle.
In depth
Tests can be moderated or unmoderated, in person or remote, on prototypes or live products. A classic finding (from Nielsen) is that around five users surface most major issues. The key is to watch behavior, not just ask opinions.
Real-world example
Asking five people to 'find and buy a blue jacket' on a site, then observing where they hesitate, uncovers confusing labels and steps.
Principle
Usability Testing
Watch real people attempt real tasks — behavior over opinion.
Related terms