Usability

Usability refers to the ease of use and learnability of a human-made object or tool. The object of use can be a software application, website, book, tool, machine, process, or anything a human interacts with. A usability study may be conducted to understand the usability of the object.

Definition

The International Organization for Standardization defines usability as "The extent to which a product can be used by specified users to achieve specified goals with effectiveness, efficiency, and satisfaction in a specified context of use." The word "usability" also refers to methods for improving ease-of-use during the design process.

Goals of Usability

Usability is about making products and systems easier to use, and matching them more closely to user needs and requirements. The primary goals of usability are:

• Effectiveness: This refers to the accuracy and completeness with which users can achieve specified goals in particular environments.
• Efficiency: This refers to the resources expended in relation to the accuracy and completeness of goals achieved.
• Satisfaction: This refers to the comfort and acceptability of the work system to its users and other people affected by its use.

Usability Considerations

Usability considerations, such as the ones listed below, are integral to the design process:

• Learnability: How easy is it for users to accomplish basic tasks the first time they encounter the design?
• Efficiency: Once users have learned the design, how quickly can they perform tasks?
• Memorability: When users return to the design after a period of not using it, how easily can they reestablish proficiency?
• Errors: How many errors do users make, how severe are these errors, and how easily can they recover from the errors?
• Satisfaction: How pleasant is it to use the design?

See Also

• User Experience
• Human-Computer Interaction
• User Interface Design
• Information Architecture

References

Usability Resources
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