The autonomic nervous system is subdivided into the sympathetic and parasympathetic systems, with the vagus nerve being a key cranial nerve in the parasympathetic system.

“that system is further subdivided into the two terms you've already brought up a sympathetic system and a parasympathetic system and you've already alluded to one of the most important nerves in that parasympathetic system called the vagus nerve which is a cranial nerve”