This document provides an introduction to psychology. It defines psychology as the scientific study of mind and behavior. Psychologists study both observable behaviors and mental processes. The document outlines several early philosophers who influenced the foundation of psychology, including Plato, Aristotle, and Descartes. It describes the main goals of psychology as describing, explaining, predicting, and controlling behavior. Several major schools of thought in psychology are introduced, including structuralism, functionalism, psychodynamic, behaviorism, humanism, Gestalt, biological, cognitive, evolutionary, and social-cultural perspectives. Finally, it discusses some key issues debated in psychology such as nature versus nurture and free will versus determinism.