A light bulb is an electrical device that produces light when an electric current passes through it. It consists of a bulb that contains a filament, usually made of tungsten, that is heated to a high temperature by the electric current, producing light. The bulb is typically encased in a glass or plastic shell and connected to electrical wires that allow it to be powered and controlled. Light bulbs come in a variety of shapes, sizes, and technologies, including incandescent, fluorescent, LED, and others, and are used for a range of lighting applications, from homes and offices to streetlights and car headlights.