Positive Emotion Theory: Happiness is regarded as a positive emotion, a feeling about positive experience and emotion. In the theory of positive emotions, happiness is regarded as a psychological state, which can make people feel full, satisfied and happy.
Behaviorism theory: happiness is regarded as a function of behavior and observation, and it is the result of a specific behavior. Behaviorism theory holds that when people experience happy and satisfying events, they are more likely to show positive and happy behaviors.
Social cognitive theory: Happiness is regarded as a social and cultural experience, a kind of cognition and evaluation based on social and cultural background. Social cognitive theory holds that the essence of happiness depends to a great extent on people's cultural beliefs and social values.
Biological science theory: Happiness is considered as the result of biological evolution, which is related to the activities of the brain and nervous system. According to the theory of biological science, happiness comes from chemical and nerve reactions in the brain, such as the release of dopamine and the activation of reward system.
Although there are different theories and definitions, it is generally believed that the essence of happiness is a positive emotion and experience, which can enhance individual happiness and life satisfaction. The source of happiness also varies from person to person, which may come from many factors, such as personal internal physiological or psychological needs, social relations, culture, environment and so on. The study of the nature of happiness provides an important theoretical and practical basis for the study of individual happiness and quality of life.