Polymers are long chain molecules. They can occur naturally or be created in industry through chemical processes. Plastics are an example of a polymer made in the chemical industry.

Polymers can occur naturally and be made by all living organisms. DNA, proteins and starch are all examples of organic polymers that occur naturally.

The process in which monomer molecules join together in a chemical reaction and create polymer chains is called polymerisation. Addition and condensation polymerisation are two types of this chemical process in which polymers are formed.