Carbohydrates are one of the most important components of the body, and at the same time, they are the main components of food and the main source of energy for the human body. Carbohydrates can be divided into the following three categories according to whether they can be hydrolyzed and the products after hydrolysis, including monosaccharides, disaccharides and polysaccharides. 1. Monosaccharides: the basic unit of sugar, can not be hydrolyzed, with fast absorption, can directly provide the characteristics of energy, common monosaccharides are glucose, fructose, galactose. 2. Disaccharide: composed of two monosaccharide molecules, disaccharide digestion and absorption in the body is relatively easy, including sucrose, lactose, maltose. 3. Polysaccharides: composed of multiple monosaccharides, polysaccharides need to be gradually broken down by digestive enzymes into disaccharides and monosaccharides before they can be absorbed and utilized, including starch, cellulose, glycogen. In short, carbohydrates are very important for the human body.