3D printing is also called additive manufacturing. This term accurately describes how this technology works to create objects.
“Additive” refers to the successive addition of thin layers between 16 to 180 microns or more to create an object. In fact, all 3D printing technologies are similar, as they construct an object layer by layer to create complex shapes.
3D printing or additive manufacturing is a process of making three dimensional solid objects from a digital file.
The creation of a 3D printed object is achieved using additive processes. In an additive process an object is created by laying down successive layers of material until the object is created. Each of these layers can be seen as a thinly sliced horizontal cross-section of the eventual object.
More recently, the term is being used in popular vernacular to encompass a wider variety of additive manufacturing techniques.
3D printing is the opposite of subtractive manufacturing which is cutting out / hollowing out a piece of metal or plastic with for instance a milling machine.
3D printing enables you to produce complex shapes using less material than traditional manufacturing methods.