The five major theories of human behavior include behavioral, cognitive, psychodynamic, humanistic, and biological theories. Each offers a unique perspective on why people think, feel, and act the way they do. Understanding these approaches helps explain personal choices, social interactions, and decision-making. It also connects to broader topics like human behavior and the planet, showing how our beliefs and actions influence environmental sustainability. By learning these theories, we can better understand ourselves, improve relationships, and encourage behaviors that create a healthier future for both people and the planet.