An internist is a medical doctor who specializes in internal medicine after finishing medical or osteopathic school. These specialists apply the knowledge that they learned during their years of school and during their residencies to diagnose and treat a myriad of common and complex diseases.
Internal medicine doctors are trained to treat the majority of problems and health issues that a patient may have in his lifetime. They are trained to treat very simple diseases, such as the cold and flu, as well as complex illnesses, such as severe chronic conditions. Internists also train in preventative medicine and can provide preventative care to all of their patients.