3D printing, also known as additive manufacturing, is a process of creating three-dimensional solid objects from a digital file. The creation of a 3D-printed object is achieved using additive processes, where an object is created by laying down successive layers of material until the object is complete. Each of these layers can be seen as a thinly sliced horizontal cross-section of the eventual object. 3D printing enables you to produce complex shapes using less material than traditional manufacturing methods.
3D Printing Wiki (Reddit)
The various types of 3D printing technologies all create real-world three-dimensional objects from digital models via the addition of material. These processes are able to produce novel structures that other manufacturing techniques cannot.
Usually the 3D printing process looks like this: