Like the accessible and universal design, usable design serves to create products that are easy and efficient to use. Usability has been defined by the International Organization for Standardization as the "effectiveness, efficiency, and satisfaction with which a specified set of users can achieve a specified set of tasks in a particular environment." Usability engineers test the ease at which users can learn to operate a product and remember how to do so when they return to the product at a later time.
Unfortunately, people with disabilities are not always included in usability tests. Therefore, many products that perform well in usability tests are not accessible to people with disabilities. Increasingly, accessible and universal design considerations are being addressed by usability professionals. For example, accessibility is now a topic on high-profile usability websites such as Usability.gov and Usability First.
Usability shares some key goals with accessibility and universal design. Designers in all three disciplines seek to create product features that are easily discovered and operated by the user. Usability engineers are concerned with aspects of the user experience, that include:
- Learnability: Can users easily learn how to operate the product, and can they remember how to perform tasks when they return to the product the next time?
- Consistency: Are product features clearly and consistently labeled?
- Efficiency and effectiveness: Can users perform tasks with a minimal amount of effort and achieve their goals successfully?