The author presents single-screw extrusion technology together with the relevant polymer fundamentals, with an emphasis on screw design. The presentation begins on a physical level, providing an in-depth conceptual understanding, followed by an analytical level with mathematical models. Practical applications of the mathematical models are illustrated by numerous examples. A brief description of twin-screw extrusion technology is also presented. New in the third edition: a novel patented barrier screw design that eliminates shortcomings of all previous barrier screw designs, more descriptive specific screw design guidelines, a scientifically designed pineapple mixing section, and general improvements and corrections.