3D printing involves using additive manufacturing to create 3D objects from digital models by laying down successive layers of material. The document discusses how 3D printing works by building objects layer by layer from a digital design file. It provides examples of 3D printing technologies like RepRap, Makerbot, and Tinkercad and gives a brief history of 3D printing from its origins to current advances. The document also covers tutorials for using Tinkercad to design 3D objects.