This chapter focuses on models of decision-making and how decision-making under real-world conditions often differs from the models. Human decision making is flexible, using different strategies depending on task and situational demands. For instance, decisions-makers employ a variety of heuristics that reduce the demands of choosing among alternatives, but which can result in poor choices when applied in some situations. There are a number of different approaches to the study of decision-making, but they can be generally categorized as belonging to the normative, descriptive, or naturalistic approaches. A normative approach or model of decision-making specifies what an individual should do, given the facts of the situation. In contrast, the descriptive approach to decision-making attempts to describe how individuals actually make decisions. Naturalistic decision-making (NDM) studies individuals in real-world settings. Modern information technologies such as the web provide us with access to unprecedented amounts of information.