Usability testing is a means of understanding the goodness of a design’s fit to the intended users’ problems

“Usability testing should not be a stage gate in your design and development process. It should be a tool with which to gather helpful, diagnostic information from your target users. It’s a means of understanding the goodness of a design’s fit to the intended users’ problems.” – Paul J. Sherman
Read more in Paul’s article “Testing Your Own Designs Redux.”
Related quotes:- Focus on understanding the behavior and performance of people using a design
- The hygiene factor of usability
- Findability precedes usability. You can’t use what you can’t find.
- Peripheral insights often feed a designer’s instincts most
- Necessary and useful design should be beautiful