3D printer filament is a thermoplastic material used to create objects layer by layer in FDM 3D printing. Supplied in spools, it comes in various materials such as PLA, ABS, PETG, TPU, ASA, and Nylon, as well as specialty composites like wood PLA, glow-in-the-dark PLA, and carbon fiber PLA. Each filament type offers unique properties suited for different applications — from household items to functional mechanical parts.