An emergency physician is a doctor who is an expert in handling conditions of an urgent and extremely dangerous nature. These specialists work in the emergency room (ER) departments of hospitals where they oversee cases involving cardiac distress, trauma, fractures, lacerations and other acute conditions.
Emergency physicians are specially trained to make urgent life-saving decisions to treat patients during an emergency medical crisis. These doctors diagnose and stabilize patients before they are either well enough to be discharged, or transferred to the appropriate department for long-term care.

A geriatric specialist is a physician who treats the elderly population and the conditions that most commonly affect them. These doctors have special training in the effects of aging on the body and mind of a patient.
Geriatric specialists treat common ailments faced by senior citizens, such as frailty, incontinence, memory problems, arthritis, senility, decreased functioning and more.
In addition, geriatric specialists keep abreast of the different medications that an elderly person is prescribed to treat their more complex health issues in order to decrease adverse side effects and avoid dangerous drug interactions.

An internist is a physician who focuses on the diagnosis and treatment of conditions that affect the adult population—both acute and chronic.
These doctors are often who adults see as their primary physicians because they treat a broad range of illnesses that do not require surgical or specialist interventions. They also work to help a patient maintain optimal health in order to prevent the onset of disease.
In addition to treating the common cold and flu, internists also treat chronic diseases like diabetes and heart disease.

A family practitioner is a doctor who specializes in caring for people of all ages, at all stages of life. Rather than focusing on the treatment of one disease or patient population, family practitioners are often the doctors that people see for their everyday ailments, like cold and flu or respiratory infections, and health screenings. When necessary, family practitioners will provide referrals for conditions that require the expertise of another specialist.
The doctors may also provide physicals, inoculations, prenatal care, treat chronic diseases, like diabetes and asthma, and provide advice on disease prevention.