Polyethylene or polythene (abbreviated PE; IUPAC name polyethene or poly(methylene)) is the most common plastic.
As of 2017, over 100 million tonnes of polyethylene resins are produced annually, accounting for 34% of the total plastics market. Its primary use is in packaging.
Many kinds of polyethylene are known, with most having the chemical formulaₙ. PE is usually a mixture of similar polymers of ethylene with various values of n.
Polyethylene is a thermoplastic; however, it can become a thermoset plastic when modified.