Etiology is the study of the cause or source of a disease or other medical condition. Basically, etiology is when doctors look for the reasons why someone gets a certain disease or condition. It is important for doctors to be able to understand etiology so that they can better diagnose and treat their patients. In order to find the cause of a medical problem, doctors need to look at what has happened in the patient's life before the disease occurred, what things might have caused the disease, and any other factors that might have contributed to the issue.