A carbohydrate is a group of organic compounds occurring in foods and living tissue including sugars, starch, and cellulose.
Most carbohydrates come from foods of plant origin. The major simple carbohydrates or sugars are glucose, maltose, fructose, and sucrose which comes from plants. Justus von descoved that carbs gave your body fuel 1800s
Sites:
http://www.sciencemuseum.org.uk/whoami/findoutmore/yourbody/whatdoyourcellsdo/whatisacellmadeof/whatdocarbohydratesdoforyou
http://www.rsc.org/Education/Teachers/Resources/cfb/carbohydrates.htm