A pediatrician is a doctor who specializes in the regular care of children, as well as the diagnosis and treatment of illness in children. Young patients are often more complicated to treat because they are still growing and developing.
While pediatricians may sub-specialize in specific therapy areas like oncology, surgery, ophthalmology, and anesthesiology, in general, pediatricians provide services like vaccinations, health exams, and treatment of common ailments and injuries. In addition, pediatricians are trained to handle the complex emotional and behavioral issues faced by children, especially during puberty.
Pediatricians normally see their patients from birth until the age of 18, although some may agree to treat patients into their early 20s, if requested.

A gastroenterologist is a specialist in diagnosis and treatment of conditions involving the digestive/gastrointestinal (GI) tract. These doctors are experts on how food moves through the digestive system and is chemically broken down, with nutrients being absorbed and waste excreted. You might see this kind of doctor if you are experiencing any number of stomach issues, some of which might be severe diarrhea, irritable bowel syndrome, hemorrhoids, ulcers, acid reflux, Crohn's disease and more.

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 otolaryngologist is more commonly referred to as an ENT, someone that can treat medical issues you may be having with you ears, nose, or throat. This is a physician who is specially trained to diagnose and treat conditions of the ear, nose, sinuses, larynx (voice box), mouth, throat, head, and neck. These doctors treat patients through both medical and surgical means. For instance, an otolaryngologist may treat an obstruction of the nasal passage, caused by malformation of the nose, through rhinoplasty.

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 urologist is a physician who specializes in diagnosing and treating conditions affecting the male reproductive system, as well as the urinary tracts of both males and females.
These doctors cover the kidneys, ureter, urinary bladder, adrenal glands, urethra, and the male reproductive organs which include the testes, epididymis, vas deferens, seminal vesicles, prostate and penis. Some common disorders that urologists treat are urinary tract infections (UTI), stress incontinence, benign prostatic hyperplasia, kidney stones, erectile dysfunction, kidney cancer, prostate cancer, testicular cancer, and cystitis. These urological specialists also perform vasectomies and vasectomy reversals.

An obstetrician & gynecologist, or OB/GYN, is a physician who cares for women throughout their pregnancies, straight through to the delivery of their baby (obstetrician). They also specialize in annual care, as well as the diagnosis and treatment of disorders of the female reproductive system (gynecologist). Many physicians specialize in both of these fields in order to provide complete overall health services to women at every stage of life.

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.