Plastic deformation processes are presented not only as methods for shaping workpieces, but also as means to alter their microstructure and properties inherited from the solidification stage. A first category, referred to as primary or rough deformation processes, is typically conducted at high temperatures and serves to refine and homogenize the original solidification structure. Subsequent secondary or finish forming processes are generally performed at room temperature to achieve tighter dimensional tolerances, improved surface finishes, and enhanced mechanical properties. The chapter then explores microstructural evolution during hot and cold deformation, highlighting key concepts such as strain hardening, annealing, recovery, recrystallization, including aspects related to continuous recrystallization, and severe plastic deformation. A final section focuses on the hot workability of alloys, examining how microstructural features influence a material’s ability to undergo plastic deformation.