Filament is a thin, flexible strand used in various applications, most commonly in 3D printing. It is typically made from materials like PLA (polylactic acid) or ABS (acrylonitrile butadiene styrene), which are heated and extruded through a nozzle to create three-dimensional objects layer by layer. In addition to 3D printing, filaments are also found in light bulbs, where they serve as the wire that glows when electricity passes through. These filaments can be made from materials like tungsten, which has a high melting point, allowing it to produce light efficiently without burning out quickly.