Personality disorders are conditions where an individual's thoughts, feelings and behaviors differ significantly from societal norms. About 5-15% of adults have at least one personality disorder. They are grouped into three clusters based on characteristics: Cluster A includes paranoid, schizoid and schizotypal disorders; Cluster B includes antisocial, borderline, histrionic and narcissistic disorders; and Cluster C includes avoidant, dependent and obsessive-compulsive disorders. Borderline personality disorder is characterized by unstable moods and relationships, impulsivity and difficulty regulating emotions. Treatment involves therapy such as dialectical behavior therapy and medication management. Nursing care focuses on safety, support, consistency and helping patients develop coping skills.