A senior house officer is a classification of a doctor found in the United Kingdom but not in the United States. They are junior doctors, similar to residents in the United States, who are in training to become specialists.
Like residencies in the United States, senior house officers work with trained doctors to learn and gain hands-on experience before opening their own practice or joining a hospital staff.
Being a senior house officer is a temporary job. Most posts last a few months at a time, as senior house officers often work in a few different hospitals and clinics during the term of their apprenticeship.
According to the Royal Infirmary of Edinburgh, senior house officers often serve as the principal surgeon on many routine operations. These procedures include appendectomies, varicose vein surgeries and more.