A personality disorder is a pattern of feelings, thoughts and behaviours that may have been with you for a long time. Personality disorders affect the way you understand yourself, the way you react to the world around you, the way you cope with emotions and the way you navigate relationships. Having a personality disorder does not mean that there is something wrong with your personality—it simply means that you have a pattern of feelings, thoughts and emotions for a long time that causes problems.
In the past, people thought that someone with borderline personality disorder (BPD) was "on the borderline" between psychosis and neurosis (anxiety/depression). Today, we know much more about BPD, and there is more research on BDP than any other personality disorder.