What is carbohydrates? Unlikely you are interested in their chemical formula, I can only say that the total for this type of nutrients is the presence in the molecule of carbon and water.
Carbohydrates entering the body with food, are divided into simple and complex is the structure, but the properties they are digestible, partially digestible and indigestible.
Simple carbohydrates consist of 1-2 molecules, also called mono - and disaccharides: is glucose, galactose, fructose, sucrose, lactose, maltose. Due to its structure simple sugars are easily broken down in the digestive tract and also easily absorbed, so they are called light.
Complex carbohydrates and therefore complex, that have large multi-component molecules, and in special literature you can meet them called "polysaccharides". These include starch, glycogen (synthesized and stored in the liver and to a lesser extent muscle), inulin, cellulose, pectin, etc.
The main role of carbohydrates is to provide the body with energy released during the breakdown of their molecules into carbon dioxide and water. Energy is measured in kilocalories. In the cleavage of 1 g of carbohydrate is provided with 4 kcal of energy. In addition, carbohydrates are part of hormones, enzymes, and various body fluids.
Indigestible carbohydrates improve digestion — give the gut a normal environment for the habitat of beneficial microbes, normalizes motor activity.