Polymerization is the process where monomers—or single molecules like amino acids and hydrocarbons—bond to create polymers.
There are two kinds of polymers. The first are natural polymers, like deoxyribonucleic acid (or DNA), cellulose and rubber. The second are artificial or man made polymers, such as those found in polyvinyl chloride or PVC and other plastics.
There are different ways for polymerization to occur. For example, some monomers tend to change dramatically once they bond; others retain their original structure no matter how many are added (think of how you can pile an infinite number of Lego pieces on top of one another in increasingly complex ways, and yet you can still work out the individual blocks). This is called "addition polymerization.”
However, in some cases bonding processes changes the monomers. For example, in “condensation polymerization” the monomers lose some of their mass, leading to a new product that is “condensed.” For example, if kids want to make a building out of soda cans instead of Lego blocks, they will have to drink the contents of the cans. So, ironically, their creation of 10 or more cans can actually weigh less than 1 original can.
Polymerization can also differ in the way the monomers combine. In “chain growth polymerization” the monomers are added one at a time, like links to a chain.
Polymers are crucial to all existence, being the building block of the building block of life: DNA. They are also the stuff by which the human brain is made of.