The manufacturing process for preparing very thin polymer products has developed into what is arguably the largest outlet for synthetic polymers. The central theme of this volume is the developments in process hardware and operating techniques that permit increasingly high production rates, optimum property development, unusual degrees of molecular orientation, and the coextrusion of multi-layer, multi-component film and sheet. The strong relationships and the interdependence of these developments on the achievements in polymer design, such as rheology and mechanical and optical properties, are also discussed.