Carbohydrates are chemical compounds that contain only oxygen, hydrogen and carbon. They are made up of joined-up sugars. Sugars have the general formula Cm(H2O)n, and are also known as saccharides.
Certain carbohydrates are an important storage and transport form of energy in most organisms, including plants and animals.
There are four types of carbohydrates, named by the number of sugar molecules they contain.