The primary objective of this book is to provide a comprehensive exploration of animal behavior, encompassing various dimensions of the field. We will delve into the underlying genetic and physiological mechanisms that contribute to the development and expression of behavior, unraveling the intricate interplay between genes, hormones, and neural circuits. Understanding the genetic basis of behavior allows us to appreciate the remarkable diversity and adaptive strategies displayed by animals. Moreover, we will delve into the fascinating world of animal cognition, exploring the intellectual capacities and problem-solving abilities of different species. From tool use in primates to problem-solving in birds, we will examine the fascinating ways in which animals perceive, learn, and adapt to their environment. By studying animal cognition, we gain insights into the complex cognitive processes that underpin their behaviors and allow them to navigate their world with remarkable skill and ingenuity.