What is additive manufacturing (3D printing) and what are its main technologies?

Additive manufacturing builds parts layer-by-layer from digital models, unlike subtractive methods that remove material. Main technologies include FDM (Fused Deposition Modeling) for plastics, SLA (Stereolithography) for high-detail resin parts, SLS (Selective Laser Sintering) for functional prototypes, and DMLS/SLM for metal parts. It enables complex geometries impossible with traditional manufacturing and is ideal for prototyping and low-volume production.