Additive Manufacturing, often referred to as digital 3D Printing, is a process that builds up components in layers by depositing materials in three dimensions. It is the opposite of traditional manufacturing modes as milling, turning etc. that eliminate materials from a block or an initial mold. It is therefore more efficient since it creates less waste.
Its other main advantage is that Additive Manufacturing can create parts directly based on Computer Aided Design (CAD) models and use the freedom of design without the major traditional manufacturing constraints. The development of 3D Printers allowed professionals at first, to make small parts or rapid prototypes, which could then be visualized, submitted to stress tests, or fitted to other parts.