Additive manufacturing, more commonly referred to as 3D printing, is a process of creating physical parts by building them layer by layer from digital data. Additive manufacturing builds parts by adding material only where it is needed. In some systems, additional support material is used to hold the part during the build process, but the core principle remains the same. There are many different additive manufacturing processes, each building parts in fundamentally different ways. They are all categorized as additive because they share the common approach of adding material where and when it is needed, rather than removing material (subtractive manufacturing) or relying on tooling.