What makes a product or service usable?
Usability is a quality that many products possess, but many, many more lack. There are historical, cultural, organizational, monetary, and other reasons for this, which are beyond the scope of this book. Fortunately, however, there are customary and reliable methods for assessing where design contributes to usability and where it does not, and for judging what changes to make to designs so a product can be usable enough to survive or even thrive in the marketplace.
It can seem hard to know what makes something usable because unless you have a breakthrough usability paradigm that actually drives sales (Apple's iPod comes to mind), usability is only an issue when it is lacking or absent. Imagine a customer trying to buy something from your company's e-commerce web site. The inner dialogue they may be having with the site might sound like this: I can't find what I'm looking for. Okay, I have found what I'm looking for, but I can't tell how much it costs. Is it in stock? Can it be shipped to where I need it to go? Is shipping free if I spend this much? Nearly everyone who has ever tried to purchase something on a web site has encountered issues like these.
It is easy to pick on web sites (after all there are so very many of them), but there are myriad other situations where people encounter products and services that are difficult to use every day. Do you know how to use all of the features on your alarm clock, ...