It is not true, as economic theory argues, that the behavior of the agents are rational and aimed at maximizing the usefulness: psychology has shown that human decision-making processes systematically violate certain principles of rationality. This ingenious disciplinary integration (cognitive psychology and economics) is an overturning of the cornerstones of neoclassical economics. Daniel Kahneman, a pioneer of this new stream of studies, with a series of brilliant experiments showed the importance of applying psychology to cognitive science and revolutionized the common point of view on understanding the economic decisions. His work on the psychology of attention, of judgment and of decision laid new empirical foundations for the theory of economic rationality and the disciplines of behavioral economics, cognitive economics and happiness owe a lot to this contribute. This volume collects some of the most significant pieces of Daniel Kahneman's work and provides a brief introduction to his thought.