Polyethylene, which is also known as polythene, is a thermoplastic material which can be blow moulded, extruded, injection moulded or rotational moulded. The density of the material dictates how rigid it is, high density polyethylene (HDPE) is semi-rigid whilst low density polyethylene (LDPE) is flexible.
Low density polyethylene was developed in 1933 only being used for military purposes until 1945, after which it has been used commercially. High density polyethylene was developed in 1953.
Because of its flexible nature polyethylene is used for squeezable containers. However, the material is probably best known for its home ware applications by Tupperware, and the polythene bag.
As thermoplastics, both densities of polyethylene can be easily recycled.