Low-density polyethylene (LDPE)
is a thermoplastic made from the monomer ethylene. It was the first grade of polyethylene, produced in 1933 by Imperial Chemical Industries (ICI) using a high-pressure process via free radical polymerization. Its manufacture employs the same method today. The EPA estimates 5.7% of LDPE is recycled. Despite competition from more modern polymers, LDPE continues to be an important plastic grade. In 2013 the worldwide LDPE market reached a volume of about US$33 billion.

LDPE is widely used for manufacturing various containers, dispensing bottles, wash bottles, tubing, plastic bags for computer components, and various melded laboratory equipment. Its most common use is in plastic bags. Other uses are trays and general-purpose containers, corrosion-resistant work surfaces, parts that need to be weldable and machinable, parts that require flexibility, very soft and pliable parts such as Snap-On lids, six pack rings, plastic wraps, playground slides and for packaging computer hardware.