Polyethylene is a thermoplastic polymer with a variable crystalline structure and a vast range of applications depending on the particular type. It is one of the most widely produced plastics in the world, with tens of millions of tons produced worldwide each year. The commercial process (the Ziegler-Natta catalysts) that made PE such a success was developed in the 1950s by two scientists, Karl Ziegler of Germany and Giulio Natta of Italy.  

There are several types of polyethylene, and each one is best suited for a different set of applications. Generally speaking, High-Density Polyethylene (HDPE) is much more crystalline, and is often used in entirely different circumstances than Low-Density Polyethylene (LDPE). For example, LDPE is widely used in plastic packaging, such as for grocery bags or plastic wrap. HDPE, by contrast, has common applications in construction (for example, in its use in the fabrication of drain pipes). Ultrahigh Molecular Weight Polyethylene (UHMW) has high-performance applications in things such as medical devices and bulletproof vests.