Digestion is termed as the breakdown of food which has large insoluble molecules to small soluble molecules which makes them to be absorbed in the blood plasma.
Based on the way which food is being broken, it will depend on the form of catabolism which is used in the digestion. For example, catabolism is divided into chemical and mechanical digestion where mechanical digestion breaks down large to small pieces of food.
Those pieces of food are accessed by digestive system. In chemical digestion it is the enzymes which broke down molecules of food.
