Over a century ago, William James proposed that people search through memory much as they rummage through a house looking for lost keys. Like other animal species search space, we scour our environments for territory, food, mates, and other goals, including information. We search for items in visual scenes, for historical facts and shopping deals on internet sites, for new friends to add to our social networks, and for solutions to novel problems. In all these spaces, what we find is governed by how we search and by the structure of the environment. This book explores how we search for resources in our minds and in the world.