3D printing, also known as Additive Manufacturing, is a process in which material is joined together using computer numerically controlled (CNC) machines to create a three-dimensional object.  3D printing allows for the complex shapes and objects to be manufactured precisely and quickly without the need for additional tooling.  

Printed objects usually begin as a digital 3D model from a computer aided design (CAD) file.  The file is then processed into layers, called "Slicing", which gives rise to the layer-by-layer nature in which 3D printing is usually carried out.  This production method has also enabled the manufacturing of objects that could not be previously produced using other manufacturing methods.