A personality disorder is a condition where a persons basic personality is so maladaptive, inflexible, or distressing that they cannot be included into their culture's everyday life.
As of the DSM-IV, the personality disorders are grouped into three types:
Cluster A: (odd and eccentric disorders)
Cluster B: (dramatic, emotional, and erratic disorders)
Cluster C (anxious and fearful disorders)
There is also a 'Personality Disorder not otherwise specified' category. This a catch-all category, for anything that seems to be a personality disorder but does not meet the criteria for the disorders listed above.
In America it is usual to use the DSM-IV, but the World Health Organization has put out its own set of psychiatric standards, called the ICD-10 (ICD-10 Classification of Mental and Behavioural Disorders); this is used in many parts of the world, including most of Europe. The ICD's categories are as follows: