3D printing, also known as additive manufacturing, involves building 3D objects from a digital file by laying down successive layers of material. The first 3D printer was developed in 1984 and printed objects by depositing layers of liquid, powder, or sheet material and fusing them together. Today, 3D printing technologies include fused deposition modeling (FDM), selective laser sintering (SLS), stereolithography (SLA), and binder jetting. 3D printing has applications across industries like manufacturing, engineering, healthcare, and education.