This article introduces reasons behind the selection of a deformation process as the method of choice for producing a part or product form. It discusses the advantages, disadvantages, and categories of deformation processes. The article describes major design considerations in applying a deformation process. Some fundamental aspects of plastic flow, flow stress, cold and hot working, workability, and formability are presented. The article describes free-surface cracking, central burst or chevron cracking, and cracking on die contact surface, as well as the microstructural effects on metal flow. The article also discusses defects in sheet-metal formed parts and flow-related defects in bulk forming.