What is usability?

Usability is defined as the degree to which a product can be used by specified users to achieve specified goals effectively and efficiently. This definition captures the essence of usability by emphasizing the importance of both effectiveness—which refers to users being able to accomplish their tasks—and efficiency, which relates to how quickly and easily they can achieve those tasks with the product.

A product is deemed usable when it satisfies the needs and expectations of its target users, allowing them to navigate and interact with it without excessive difficulty or confusion. This focus on the users, their goals, and the context in which they use the product is essential for creating designs that are functional and satisfactory.

In contrast, the other choices provide a different perspective that does not encapsulate the core essence of usability. A discussion of aesthetic appeal and marketing potential falls more under product design and marketing strategy rather than usability. Similarly, measuring how often a product is used speaks to its popularity rather than its usability, while the speed of prototype development relates to the design process rather than the experience of end users. Therefore, the emphasis on user effectiveness and efficiency makes the correct choice distinctly representative of what usability truly means.