The book is aimed at teaching the reader the fundamentals of single-screw extrusion such that fast troubleshooting and process optimization and design are possible. The fundamental processes that are occurring in the machine are developed from the natural reference point of a rotating screw rather the traditional rotating barrel. These fundamentals are then combined with the chemistry of polymers and the physical properties related to processing to troubleshoot and optimize extrusion processes. Many industrial extrusion problem case studies will be presented. In each case study, the root cause of the problem will be identified along with the solution.