This document discusses the two types of digestion: mechanical and chemical. Mechanical digestion is the physical breakdown of food using mechanical forces, like chewing. Chemical digestion is the breakdown of food into nutrients at a molecular level using digestive enzymes. The document then describes where each type of digestion occurs within the digestive system, including mechanical digestion in the mouth by chewing and chemical digestion by saliva breaking down carbs. It further explains mechanical and chemical digestion in other parts like the stomach and small intestine.