User-centered design means working with your users all throughout the project.

The designer has an obligation to provide an appropriate conceptual model for the way that the device works. It doesn't have to completely accurate but it has to be sufficiently accurate that it will help in both the learning of the operation and also dealing with novel situations.

Too many companies believe that all they must do is provide a 'neat' technology or some 'cool' product or, sometimes, just good, solid engineering. Nope. All of those are desirable (and solid engineering is a must), but there is much more to a successful product than that: understanding how the product is to be used, design, engineering, positioning, marketing, branding-all matter. It requires designing the Total User Experience.

Behavioral design is all about feeling in control. Includes: usability, understanding, but also the feel.

Knowing how people will use something is essential

Having the best product means nothing if the people won't buy it.

How do you discover a need that nobody yet knows about? This is where the product breakthroughs come through.