Polymers are macromolecules formed by the chemical bonding of large numbers of smaller molecules, or repeating units, called monomers. The point at which monomers or prepolymers combine to a sufficient degree in a single molecule to be specifically called a polymer is largely arbitrary. Chemistry Chapter 15 includes topics like – the terms Monomer, Polymer, Polymerisation. Classification of Polymers based on source: Natural polymers, Semi-synthetic polymers, Synthetic polymers. Category of polymers based on structure: Linear Branched-chain, Cross-linked or Network Polymers. Classification of polymers based on the mode of polymerization: Addition polymers, Condensation polymers.