This chapter discusses the concept of additive manufacturing (AM). AM is a relatively new manufacturing technology that is driven by computer-aided design in which the solid shape to be produced is first sliced from the Standard Tessellation Language file that is submitted, and tool paths are generated using an interface software and submitted to the production system. Classification of the technologies for AM is based on the raw materials that are used in the process. These categories are as follows: Liquid-based systems, Powder-based systems and Solid-based systems. Layer manufacturing techniques are moving from rapid prototyping and rapid tooling to rapid manufacturing (RM). RM of metal parts is especially suitable for the fabrication of a small number of pieces and mass customization. By this technique, it is possible achieve metal parts with excellent mechanical properties. Aside from that, the advent of the new machines equipped with different lasers may increase the accuracy and mechanical properties of the fabricated parts.