Borderline Personality Disorder is a mental illness that is characterized by unstable moods, behavior, and relationships. People with Borderline Personality Disorder may experience intense episodes of anger, depression, and anxiety. They may also have problems with self-image and identity. Some common signs of Borderline Personality Disorder include; mood swings that are intense and uncontrollable; feeling like you are constantly on edge or in danger; having a hard time controlling your emotions; feeling like there is no one in the world who understands you, or experiencing chronic problems in your relationships.