Usability measures the quality of a user's experience when interacting with a Web site
In general, usability refers to how well users can learn and use a product to achieve their goals and how satisfied they are with that process. Usability, as defined by Joseph Dumas and Janice (Ginny) Redish, means that people who use the product can do so quickly and easily to accomplish their tasks. Usability may also consider such factors as cost-effectiveness and usefulness.

Millions of Web sites offer users information, goods, services, and entertainment. But many of these sites are difficult to use, don't work properly, and ultimately don't attract or keep users. By following a usability engineering process, users' abilities to find information and satisfaction with Web sites improve significantly

Ease of learning - How fast can a user who has never seen the user interface before learn it sufficiently well to accomplish basic tasks?

Efficiency of use - Once an experienced user has learned to use the system, how fast can he or she accomplish tasks?

Memorability - If a user has used the system before, can he or she remember enough to use it effectively the next time or does the user have to start over again learning everything?

Error frequency and severity - How often do users make errors while using the system, how serious are these errors, and how do users recover from these errors?

Subjective satisfaction - How much does the user like using the system?


The first step is to clearly define your organization and users' needs, goals, and objectives. To get the project started, begin by asking yourself (and your Web development team) more detailed questions such as:

• What are your agency's primary business objectives and how do they relate the Web?
• Who are the users of Web site?
• What are users' tasks and goals?
• What information do users need, and in what form do they need it?
• What functions do users want from the Web site?
• How do users think your Web site should work?
• What are users' experience levels with the Web site?
• How can the design of your Web site facilitate users' cognitive processes?
• What hardware and software will the majority of your users use to access your site?

To create a user-centered Web site we think about the needs of web site users throughout each step in the development of web site, including:

• planning web site
• collecting data from users
• developing prototypes
• writing content
• conducting usability testing with users