Polymerization is a process of reacting monomer molecules together to form polymer chains or networks. Some synonyms for the word polymerize include chain-reaction, cross-linking, coupling, and polymerization. In all instances, the process results in a macromolecule that is stronger and more complex than the initial building blocks. For example, "chain-reaction" implies the process of a series of events that occurs to create the high molecular weight of the final compound. "Cross-linking" is a specific type of polymerization reaction that connects two or more polymer chains to create a network structure. "Coupling" describes the joining of two monomers, and "polymerization" is a broader term encompassing all kinds of reactions that result in the formation of a polymer.