An internist is not an intern, nor are they studying medicine in a neophyte position in a first year position. A medical internist (MI) is a qualified, train physician whose area of specialization happens to be internal medicine. Internal medicine, as an internist practices it, is the diagnosis and prevention and/or treatment of adult diseases. In adult years, patients frequently have diseases that may be multi-system or not easily diagnosed as a single affliction (what internal medicine specialists called undifferentiated disease processes). The medical internist therefore cannot usually act as a family physician or GP (general practitioner), but is a primary care physician, and is usually involved in the first stages of a patients complaint, when the disease itself is largely unlabeled and treatment is tentative.
They are involved exclusively with adult diseases, and are not surgical, pediatric or obstetric specialists as such; however, their knowledge of symptomatic indicators has to be fairly extensive, as a primary care MI will usually see the patient in the triage stage of the diseases treatment, and will make general recommendations from there.
As if that weren't complicated enough, an MI specialist would simply be called a physician in the Commonwealth/United Kingdom, so defining their specialty is a bit hard to pin down.
However, they can be experts in any number of fields that allow them to specialize, as long as the systems they examine touch the areas of internal medicines paradigm. These include:
How does one become an IM specialist? The procedure is roughly the same as with any other medical student, and one begins to manifest interest early on.
As early as high school, one should be especially skilled in math and the sciences (particularly biology, chemistry and anatomy). This is the largest stumbling block for most prospective medical students, but it has no shortcuts if the candidate isn't good at math and science, the candidate will not be good at medicine.
Entry level courses for a medical professional include advanced anatomy, biology, physics and organic/inorganic chemistry, as well as medical ethics and a huge body of disease/treatment and symptom study, as well as at least 4000 hours of medical internships (this is the minimal experience for competitive job placement in the current marketplace). In the meantime, one earns a bachelors degree in medical sciences or any related pre-med field.
In medical school there is heavy focus on lab work in addition to the aforementioned clinical practice, and one may work in rotating shifts in a number of medical disciplines such as pharmacology, pathology, microbiology and medical law. Regardless of the later adult specialization of the IM specialist, there will be immense practical training in family practice, surgery (assistive), gynecology, obstetrics, pediatrics and even psychiatry. Students are trained to examine and diagnose patients under a qualified doctors supervision.
Essentially, the interning training runs eight years, including the time in residency, and another two years of training is necessary before licensure and certification is granted specific to the IM category (there is, after the initial eight years, a conditional registration period during which the IM fine-tunes his/her training).
The job market is fairly prosperous for the internist right now, however, and most candidates report it to be a rewarding and fascinating career path.