More specifically, starch is a polymer made of long chains of glucose monomers. These chains can be either:

* Amylose: A straight chain of glucose molecules linked by alpha-1,4-glycosidic bonds.

* Amylopectin: A branched chain of glucose molecules linked by alpha-1,4-glycosidic bonds in the straight chains and alpha-1,6-glycosidic bonds at the branch points.

The ratio of amylose to amylopectin in starch varies depending on the source (e.g., potatoes, corn, rice). This ratio affects the properties of the starch, such as its ability to gel, thicken, and form retrograded starch.