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.