PGY

PGY, short for postgraduate year, refers to a North American numerical scheme denoting the progress of postgraduate dental, medicine, podiatry or pharmacy residents in their residency programs. It is used to stratify responsibility in most training programs and to determine salary. The grade of the resident is denoted with a numeral after the PGY designation, such as PGY-3 for a third-year resident.
The length of residency depends mostly on the field a graduate chooses to take. Medical specialties such as family medicine and internal medicine often requires three years, whereas surgery usually requires a minimum of five, and neurological surgery is the longest at seven years. Subspecialization (vascular or orthopedic spine surgery as a branch of surgery, for example) in any field will add time to postgraduate training.
For more information on specific medical residency programs, see the American Medical Association's Fellowship and Residency Electronic Interactive Database.
Dental residencies for general practice, known as GPRs, are generally one year, with a possibility of a second year at some facilities. Dental specialties, such as orthodontics, require 2–4 years, while oral and maxillofacial surgery requires 4–6 years. Some specialty programs require that applicants have completed at least a one-year GPR residency, while other programs require applicants to have some private practice experience as a general dentist. Regardless of requirements, completing a GPR residency will make an applicant more competitive for any specialty program. 
Medical physics residencies range between two and four years, with at least two years fulfilling the necessary clinical experience. Completion of a CAMPEP-accredited residency allows one to sit for board examinations administered through the American Board of Radiology. PGY-3, and/or if also available -4, generally consist of scholarly research years, akin to a postdoctoral research position. Residencies options are either radiation oncology physics or medical imaging.
Pharmacy residencies are usually one year, but a PGY-2 can be completed, often as an option, for pharmacy specialties such as critical care, cardiology, oncology, etc.
In some teaching institutions, trainees are required to indicate level of training on all signatures (John Doe, M.D., PGY-1 or R-1; or John Doe, D.O., PGY-1 or R-1).
Residencies are also offered for those in the physician assistant profession in a variety of specialties such as surgery and emergency medicine.
Internships and residencies are also offered for those who have completed graduate education in psychology, known as interns and post-doc fellows.