Excretion is the natural biological process it is happened in all living organisms.It is the removal of waste materials and toxic materials from body .During the feeding we eat too much which is more than our need so the waste material is harmful for body and body releases these toxic materials. Skin, kidneys ,liver are the excretory organs.excretion is the essential property of life.                                                                                                                                                    In summer swat is coming out of body . After our feeding this food is break down and converted in glucose due to which Carbon Di Oxide is excreted out of body. Ammonia is produce by proteins coming out of body through liver . If this left out in the body then it is harmful and may causes the poison.The acid in our stomach helps to break down the food and digestion of food take place.                                                                                                                                  Water  plays key role in this process and almost 70% of our blood plasma is consist of water large number of reaction take place in the body or inside the living organism the products of these reaction are called as metabolites some of them are poisons.These excretory products may be CO2 ,uric acid , NH3 , and urea.