A Medicare Supplement (Medigap) policy is health insurance sold by private insurance companies to fill the gaps in Original Medicare Plan coverage. Medigap policies help pay some of the health care costs that the Original Medicare Plan doesn't cover.
Internal Medicine encompasses the care of all adults, healthy and sick. Internists (as all doctors who complete an internal medicine residency are called) can be generalists or subspecialists, like cardiologists or rheumatologists. If you choose not to subspecialize, you are known as a General Internist.
In modern urban practice, most internists are subspecialists: that is, they generally limit their medical practice to problems of one organ system or to one particular area of medical knowledge. For example, gastroenterologists and nephrologists specialize respectively in diseases of the gut and the kidneys.