The document discusses various defense mechanisms, which are unconscious strategies used to protect oneself from anxiety and unpleasant emotions. It categorizes defense mechanisms into primitive (e.g., denial, regression, projection) and mature forms (e.g., sublimation, altruism, self-assertion), highlighting their significance in psychological behavior and coping with stressors. The author also notes that while these mechanisms are learned in childhood, they can be modified as individuals mature.