The definition of usability is sometimes reduced to “easy to use,” but this over-simplifies the problem and provides little guidance for the user interface designer. A more precise definition can be used to understand user requirements, formulate usability goals and decide on the best techniques for usability evaluations. An understanding of the five characteristics of usability – effective, efficient, engaging, error tolerant, easy to learn – helps guide the user-centered design tasks to the goal of usable products.
- Usability means thinking about how and why people use a product.
Good technical writing, like good interaction design, focuses on user’s goals. The first step in creating a usable product is understanding those goals in the context of the user’s environment, task or work flow, and letting these needs inform the design.
- Usability means evaluation.
Usability relies on user-feedback through evaluation rather than simply trusting the experience and expertise of the designer. Unlike conventional software acceptance testing, usability evaluation involves watching real people use a product (or prototype), and using what is learned to improve the product.
- Usability means more than just “ease of use”
The 5 Es – efficient, effective, engaging, error tolerant and easy to learn – describe the multi-faceted characteristics of usability. Interfaces are evaluated against the combination of these characteristics which best describe the user’s requirements for success and satisfaction.
- Usability means user-centered design
Users are satisfied when an interface is user-centered – when their goals, mental models, tasks and requirements are all met. The combination of analysis, design and evaluation all approached starting from the user’s point of view creates usable products.
Read the well written, in-depth post by Whitney Quesenbery on her site here: http://www.wqusability.com/articles/more-than-ease-of-use.html