To a greater extent than any other creature, we humans shape the world around us to suit ourselves. Some of that shaping is unintentional, but much of it is deliberate. We create our environments by constructing buildings, roads, furnishings, and landscapes. We make our daily lives easier and more enjoyable by inventing tools, from kitchen utensils and earth-to-orbit spacecraft to social networking and enterprise-spanning IT systems. We communicate with one another in text, imagery, motion, and sound. We even attempt to craft perfect experiences in retail settings and amusement parks. This intentional shaping of the world for mass consumption is often referred to as design.
Clearly, "design" is an incredibly broad term. Do choosing what color to paint your bedroom, sculpting the exterior of a car, and planning a complex application's technical architecture all have equal claims to the word? People outside of design professions have difficulty drawing the line, and there are so many philosophies and assumptions attached to it that even designers seldom agree on exactly what "design" is.
All of this explains why most design books begin with some definition of the word. For the purposes of this book, at least, design is the craft of visualizing concrete solutions that serve human needs and goals within certain constraints.