Personality disorders are like tips of icebergs. They rest on a foundation of causes and effects, interactions and events, emotions and cognitions, functions and dysfunctions that together form the patient and make him or her what s/he is.  
The DSM uses five axes to analyze, classify, and describe these data. The patient (or subject) presents himself to a mental health diagnostician, is evaluated, tests are administered, questionnaires fulfilled, and a diagnosis rendered. The diagnostician uses the DSM's five axes to "make sense" and meaningfully organize of the information he had gathered in this process. 

Axis I demands that he specify all the patient's clinical mental health problems that are not personality disorders or mental retardation. Thus, Axis I includes issues first diagnosed in infancy, childhood, or adolescence; cognitive problems (e.g., delirium, dementia, amnesia); mental disorders due to a medical condition (for instance, dysfunctions caused by brain injury or metabolic diseases); substance-related disorders; schizophrenia and psychosis; mood disorders; anxiety and panic; somatoform disorders; factitious disorders; dissociative disorders; sexual paraphilias; eating disorders; impulse control problems and adjustment issues. 

We will discuss Axis II at length in our next articles. It comprises personality disorders and mental retardation (interesting conjunction!). 

If the patient suffers from medical conditions that affect his state of mind and mental health, these are noted under Axis III. Some psychological problems are directly caused by medical issues (hyperthyroidism causes depression). In other cases, the latter are concurrent with or exacerbate the former. Virtually all biological illnesses may provoke changes in the patient's psychological make-up, behavior, cognitive functioning, and emotional landscape. 

But the machinery of life - both body and "soul" - is reactive as well as proactive. It is molded by one's psychosocial circumstances and environment. Life crises, stresses, deficiencies, and inadequate support all conspire to destabilize and, if sufficiently harsh, ruin one's mental health. The DSM enumerates dozens of adverse influences that should be recorded by the diagnostician under Axis IV: death in the family or of a close friend; health problems; divorce; remarriage; abuse; doting or smothering parenting; neglect; sibling rivalry; social isolation; discrimination; life cycle transition (such as retirement); unemployment; workplace bullying; housing or economic problems; limited or no access to health care services; incarceration or litigation; traumas and many more events and situations.