Polymer is a substance collected of molecules with large molecular mass collected of repeating structural units, or monomers, connected by covalent chemical bonds. The word is resulting from the Greek, πολυ, polu, "many"; and μέρος, meros, "part". Well known examples of polymers contain plastics, DNA and proteins.
While the term polymer in popular usage suggests "plastic", polymers consist of a large class of natural and synthetic materials with a variety of properties and purposes. Natural polymer materials such as shellac and amber have been in utilize for centuries. Biopolymers such as proteins (for example hair, skin and division of the bone structure) and nucleic acids take part in crucial roles in biological processes. A variety of other natural polymers survive, such as cellulose, which is the major constituent of wood and paper.