Sugars and polymers of them are known as carbohydrates because their general formulas can all be written in a simple form as (CH2O)x, as if they were a hydrated form of carbon. Another term used to describe sugar-based molecules is rooted in the word "saccharide" (from the Latin, saccharum, meaning sugar).

Single units of sugar, such as glucose, are called monosaccharides. Sugars can be readily linked together to form disaccharides (contains two sugars), oligosaccharides (contains several sugars) and polysaccharides (contains many sugars).