Answer: Autonomic nervous system is made up of 3 divisions; Sympathetic nervous system, parasympathetic nervous system and sympathetic division. All these divisions are involuntary actions where parasympathetic is ultimately responsible for the "rest and digest" part of it. When the body is at rest the parasympathetic nervous system inhibits or lowers high energy requiring bodily functions.
This nervous system will lower any fight or flight response actions such as the release of epinephrine into the blood and enable digestion, urination and defeacation. When engaged in digestion you feel relaxed and at rest, this is solely due to the parasympathetic nevous system.