3D printing is a process where material is joined or solidified under computer control to create a 3D object based on a digital 3D CAD file.
3D printing works by joining or solidifying materials like plastic, resin, or powder to form a physical object. A 3D CAD file directs the printer, specifying what material to extrude and where, layer by layer, to build the final 3D shape.
For a visual explanation, watch the short video below that introduces the basics of 3D printing.