Polyethylene is a class of thermoplastics practically ubiquitous in consumer products. In its foam form, polyethylene is used in packaging, vibration dampening and insulation, as a barrier or buoyancy component, or as material for cushioning. It is most frequently seen as a packaging material.

Sixty million tons of polyethylene is produced worldwide each year, which is even more than it sounds like when you consider its low density. In the UK, polyethylene is known as polythene. Worldwide, the material is sometimes abbreviated as PE.

Polyethylene is produced through the polymerization of ethylene. Like other polymers, polyethylene is made up of huge chains of ethylene and has a molecular weight in the millions. These chains stick together through weak Van der Waals forces, meaning the material can be ripped apart by human hands. Polyethylene with different densities or material properties is created by using different catalysts during the polymerization process. For example, HDPE (high density polyethylene) is produced with the catalyst chromium, which causes the molecular chains to branch less and therefore possess a higher density.

Polyethylene is buoyant, making it popular for nautical uses. Most types of polyethylene are non-abrasive; serve as a thermal insulator; are inert to water, grease and solvents at typical temperatures; are CFC-free and ozone friendly, recyclable, odorless, and very lightweight. Many types of polyethylene are approved for use in the food industry.

Found in all types of packaging, polyethylene is used to wrap furniture, computer components, electronics, sporting goods, plants, frozen foods, clothing, bowling balls, signs, metal products, and more. It comes in forms designed to minimize static or maximize thermal insulation, among dozens of other variants. The material is impervious to bacteria and mold and is tear-resistant. Polyethylene is among the cheapest of artificially fabricated materials, but not as cheap as most raw materials, as the polymerization process consumes energy. In addition, distribution costs are normal because polyethylene cannot be compressed much for shipping.