Plastic originates in the living world around us from basic chemical elements such as carbon, oxygen, hydrogen, nitrogen, chlorine, and sulfur. Most plastic is produced from hydrocarbons derived from fossil fuels such as natural gas and oil.

In order to begin the plastic production process, heavy crude oil must be distilled and separated at high temperature and pressure into lighter groups called fractions. Each fraction is a mixture of hydrocarbon chains, composed of the elements hydrogen and carbon, which differ in terms of molecular size and structure. One of these fractions, naphtha, is the basis of all plastic production.

During the cracking process, naphtha is broken down into smaller building blocks known as monomers, such as ethylene, propylene, and butylene. These different types of monomers are used to create plastics with diverse properties. During a chemical process called polymerization, monomers are combined to create long molecular chains known as polymers. There are two main polymer families that determine the physical characteristics of plastic: thermoplastics and thermosets.