Anesthesiology, like all medical disciplines, is sufficiently complex that it is divided into several sub-fields or subspecialties. While initially trained in anesthesiology as a whole, as they move through residency training, anesthesiologists choose to specialize in a particular area. Different surgical procedures require that patients be anesthetized in different ways or using different agents. Patients in special conditions, such as pregnant women or children require special care and attention when given anesthetic. Different procedures require that the anesthesiologist be aware of the functioning of different bodily systems, organs, or biological processes, and that they be able to monitor these during a procedure. Understanding the variety of anesthesia subspecialties will allow you to understand what your anesthesiologist will be doing during your procedure.