What is sympathetic and parasympatheticc system?give examples

Sympathetic Nervous System: It is a part of autonomic nervous system which mobilizes the nervous system when the body is in action mostly during stress. .

Parasympathetic Nervous System: It is one of the most important divisions of autonomic nervous system which regulates the activities that occurs unconsciously like salivation, urination, defecation, digestion etc. It mostly governs the activities of internal organs and glands.

Both sympathetic and parasympathetic nervous system are antagonist (opposite) to each other. For example stimulation by sympathetic system increases heart beat where as stimulation by parasympathetic system decreases heart beat.