The first year of residency is traditionally called "internship" or your intern year. The years following are residency. If you wish to subspecialize (ie, Cardiology is a subspecialty of Internal Medicine, Surgical Oncology is a subspecialty/fellowship after General Surgery residency), then you will do further training as a fellow - usually 1-3 additional years.
There are other options to doing a residency, but do not expect to work as a physician or be hired by any reputable faciliy without being residency trained. In addition, some insurance companies will not pay for treatments done by those who are not fully trained and patients are ever more savvy and many expect their physician to be Board Certified.
There is a thread on the Pre-Allo Forum which talks about other options - mostly Sales, Hospital Admin, etc. for those not wishing to complete a residency (or maybe being an author like Michael Crichton).