It frustrates me to no end when someone mentions usability but clearly demonstrates that he or she doesn’t know what usability is all about.

Recently, I attended a conference where the speaker mentioned that deciding whether or not an application should open in a new window is a “decision that needs to be made with usability in mind.” I’ve also heard product demos where software engineers will say, “We changed around a lot of the interfaces to improve usability.” These people were only half right.

Of course, it makes a difference when you design an application with the user in mind. But until you run an actual scientific test, you aren’t ensuring that your application is usable at all.

When you build an interface, you are making a guess as to what would be the best way to visually represent an information space. Until you do an actual usability test, you are tossing guesses up into the air, hoping they’ll land where they are supposed to.

A usability test involves sitting down in front of your interface (whether it’s on paper or a computer screen) with a user and having them perform tasks using the interface. You keep your mouth shut while this goes on, even if the user is failing. And you observe what they do, not listen to what they say.

A prime example of the importance of actions over words was when I worked in education, and our online registration used a cart metaphor. A user claimed that the cart metaphor was kind of awkward with an abstract concept like a course. But he completed the task of registering for multiple courses without any problems at all.

Usability testing simulates how people will use your interface and how intuitive it is. You would be surprised at what details people will trip up over. And you will rarely develop an interface that won’t have any usability problems. Out in the real world, when people are using your website, computer application, remote control, or Gadget X, you will not be over their shoulders to tell them where to click or what button to push.

Please spare the rest of us and not mention usability until you actually do the work to make it usable!