Sense gap. Design begins with a perception of a gap in the user experience. Without
a gap, there is no motive for design. The gap may be perceived by users themselves
or by observers.
Define problem. In effect, problem definition is the creation by the designer of an
explanation of why the user experiences a gap. This diagnosis can be thought of as
an identification of user needs that are not being met in the current state and/or the
recognition of criteria for a high-quality solution. Problem definition is implicit in
many design efforts, particularly when users are themselves designers, but is
generally an explicit part of professional design efforts, expressed in the form of a
design brief, customer needs list, or other document. Chapter 3 focuses on problem
definition.
Explore alternatives. Given a problem, designers almost always explore
alternatives. (This step is sometimes called search.) I devote Chapter 4 to exploration.
Select plan. Exploration typically exposes more than one solution, so design requires
some sort of evaluation and selection from among alternatives. Some designers
consider many alternatives simultaneously when selecting a plan. Others articulate,