A polymer may be defined as a high molecular weight compound formed by the combination of a large number of one or more types of small molecular weight compounds.
The small unit(s) of which polymer is made is (are) known as a monomer.
The polymerization may be defined as a chemical combination of a number of similar or different molecules to form a single large molecule.
The transformation of ethene to polythene and interaction of hexamethylene diamine and adipic acid leading to the formation of Nylon 6, 6 are examples of two different types of polymerisation reactions.
A polymer which is obtained from only one type of monomer molecules is known as a homopolymer.
Example: polythene, PVC, PAN, Teflon, Buna rubber etc.