Polymerization is a chemical process where small molecules, called monomers, join together to form a larger, more complex structure known as a polymer. This process can occur through various methods, including addition and condensation reactions, and is essential in creating materials like plastics, rubber, and fibers. During polymerization, the properties of the resulting polymer can vary significantly based on the type of monomers used and the conditions of the reaction. Common examples of polymers include polyethylene, used in plastic bags, and nylon, used in clothing and ropes.