We continually hear the words usability and user-centered being used, but do we really understand that these terms mean? In Donald Norman's popular book, The Design of Everyday Things, usability is based on how people interact with objects. His illustrations stress the need to make products and systems usable and understandable. The key to design is to make sure the user can figure out what to do and also understand what is going on. This includes appropriate clues so the user can make the appropriate actions -- the appropriate actions should be intuitive. In the design of web environments this includes, among other things, the words we use, the navigation we choose, and the layout of a Web site as a whole as well as its individual pages.

Reading Norman's book may make us chuckle at how poorly designed some things are but it can cause us to pause and reflect on the usability of anything we design. The examples of a telephone or an electronic gadget like a VCR with pages of instructions, buttons with arbitrary order, lack of natural relationships, and confusing oversimplifying diagrams are easy for one to relate to. In the world of the World Wide Web we find pages and sites with similar issues when we have no idea of where to go and what to do or cannot even figure out what is the point of the page or site.

So just how do things become unusable? If one applies Norman's list of what makes things unusable, we create an environment where the necessary actions are invisible by using non-obvious commands, acronyms and techno jargon. Messages are uninformative and actions are illogical. And be sure to be inconsistent; pages should be totally different from one another and not conform to accepted standards. Even though we feel we would never do these things unintentionally, we might. Instead, we should strive to follow Jacob Nielsen's usability heuristics which stress visibility where the users are kept informed of what is going on and given appropriate feedback. Words, phrases and concepts are familiar to the user; there is natural and logical order, relevant information, consistency and standards. There is also flexibility and good messages that reduce memory load by making things recognizable rather than relying on recall.

The bottom line is that in order to make systems usable one needs to do usability testing. Without user testing and input from our users, we may have a tendency to design for our own needs and tasks that could be different from those of our users. Usability testing is concerned with testing to see if designs are intuitive, but it also needs to be concerned with understanding the community of users who will be using the system and the actual tasks they will need to accomplish. Many times we think of usability in terms of accessibility or "look and feel" but it goes far beyond that. The ISO definition refers to usability as the effectiveness, efficiency, and satisfaction in the context of realistic tasks that are performed by the intended users; in other words, systems need to be designed that are easy to use, efficient, and pleasant to use. Internal and external consistency is important so that users can learn something once and apply it again not only in the current environment but in other environments as well.

Usability must be thought of in the context of the actual tasks that something will be used for. This will be different in different settings; as an academic setting may be different than a corporate one. There can also be different desirable levels of usability especially in learning environments where a less usable system may be acceptable because it is the user's job to learn. What is important is that usability testing analyzes the intended users and their tasks; the design draws on what the intended users know, makes sense for the required tasks, and is consistent across this and other environments.

Ben Shneiderman's book Designing the User Interface, now in its fourth edition, uses the term usability engineering where designs are based on the careful observation of the users and where design is a dynamic process which can change at any time based on prototyping, usability and acceptance testing. There are many user testing techniques including focus groups, interviews, talk-aloud, questionnaires, observations, and card sorting. Yet there are limitations to usability testing and any design should be supplemented with other evaluation tools such as expert reviews, cognitive walkthrough, heuristic evaluation, and surveys. These all focus on an evolutionary development that goes on during the whole design process. Even after system release continued evaluation and revision is essential.

Usability engineering for library web pages, is this overkill? How did we get here from the simple desire to create systems that are usable? Though all this testing and retesting may seem a bit daunting, any usability testing is better than none. Some simple techniques will yield a wealth of information that help us focus on what is understandable for our users, what is relevant for our users, and the tasks that need to be accomplished. When we think of our community of users and how our web sites are used, we can see that the impact of unusable designs can be non-use, the use of competitive environments such as Google, frustration, and negative perceptions of our online library resources. Whether it is called usability, user-centered design, or usability engineering, current learning theory is stressing the need to design environments that help users focus their cognitive resources on the learning task. Keeping usability and usability testing in the forefront of our designs and creating an environment that is continually being evaluated will help our users to use these environments and allow them to focus their attention on the tasks at hand. This will ultimately help our users -- that is what usability and user-centered design are all about.