Personality disorders (PD) are a class of mental disorders characterized by enduring maladaptive patterns of behavior, cognition, and inner experience, exhibited across many contexts and deviating from those accepted by the individual's culture. These patterns develop early, are inflexible, and are associated with significant distress or disability. The definitions vary by source and remain a matter of controversy. Official criteria for diagnosing personality disorders are listed in the sixth chapter of the International Classification of Diseases (ICD) and in the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders (DSM). Personality, defined psychologically, is the set of enduring behavioral and mental traits that distinguish individual humans. Hence, personality disorders are defined by experiences and behaviors that deviate from social norms and expectations. Those diagnosed with a personality disorder may experience difficulties in cognition, emotiveness, interpersonal functioning, or impulse control. For psychiatric patients, the prevalence of personality disorders is estimated between 40 and 60%. The behavior patterns of personality disorders are typically recognized by adolescence, the beginning of adulthood or sometimes even childhood and often have a pervasive negative impact on the quality of life. Treatment for personality disorders is primarily psychotherapeutic. Evidence-based psychotherapies for personality disorders include cognitive behavioral therapy, and dialectical behavior therapy especially for borderline personality disorder. A variety of psychoanalytic approaches are also used. Personality disorders are associated with considerable stigma in popular and clinical discourse alike. Despite various methodological schemas designed to categorize personality disorders, many issues occur with classifying a personality disorder because the theory and diagnosis of such disorders occur within prevailing cultural expectations; thus, their validity is contested by some experts on the basis of inevitable subjectivity.