Polymerization is defined as the addition of two or more small molecules [known as monomers] to form a larger molecule [known as the polymer] with or without the elimination of simple compounds such as water or methanol.
There are two types of polymerization
1. Addition polymerization - This involves the formation of the polymer WITHOUT the elimination of any simple compound.
2. Condensation polymerization - The polymer is formed from the monomers by the elimination of some simple compounds.