Source: Roberts, E. (2021, November 29). Guide to the Doctor Hierarchy [Digital image]. Retrieved May 27, 2022, from https://www.verywellhealth.com/types-of-doctors-residents-interns-and-fellows-3157293.
First-year residents are referred to as interns. After that, they are known as resident doctors, resident physicians, or simply "residents".
Fellowship is optional but is required to practice certain subspecialties.
Bibliographic reference: Whitlock, J. (2021, November 29). Doctors, Residents, and Attendings: What's the Difference? Verywell Health. Retrieved May 27, 2022, from https://www.verywellhealth.com/types-of-doctors-residents-interns-and-fellows-3157293.