Internal Medicine is a specialty branch of medicine that focuses on the diagnosis of diseases and the treatment of adults.  Specialists of Internal Medicine are referred to as Internists, (not to be mistaken for interns).  Internists are equipped to treat the "whole" patient, having dedicated a number of years post-medical school to highly-specialized training.  These physicians are prepared to meet the patient's medical issue, no matter how common or complex, from managing severe chronic illnesses, to managing comorbid illnesses occurring simultaneously. 

Doctors of Internal Medicine are commonly referred to as, "the doctor's doctor" because Internists manage both common and complex diseases, and in doing so, serve as primary care physicians and as consultants to other medical specialists for the purpose of coordinating and managing treatment.  Internists provide comprehensive medical care, most often in private practices (e.g., office, clinic settings), and also care for patients in hospitals (including intensive care units) and other care facilities (e.g., nursing homes and long term care facilities).