This document defines consumer behavior and discusses its importance in marketing. It begins by defining consumer behavior as the process by which individuals decide what to purchase, when, where, how, and from whom, based on two definitions. It then lists the five disciplines that consumer behavior draws from: psychology, sociology, anthropology, economics, and marketing management. Next, it provides several reasons for studying consumer behavior, such as understanding customer preferences, developing better marketing strategies, and avoiding market failures. It concludes by outlining some key characteristics of consumer behavior and defining different types of consumers.