The incandescent light bulb or incandescent lamp is a source of artificial light that works by incandescence (a general term for heat-driven light emissions which includes the simple case of black body radiation). An electrical current passes through a thin filament, heating it until it produces light. The enclosing glass bulb prevents the oxygen in air from reaching the hot filament, which otherwise would be destroyed rapidly by oxidation.

Incandescent bulbs are sometimes called electric lamps, a term originally applied to the original arc lamps. They are also known as globes and light globe with the theater, television and film industries, a term which is commonly used in Australia.

Incandescent bulbs are made in a wide range of sizes and voltages, from 1.5 volts to about 300 volts. They require no external regulating equipment and have a low manufacturing cost, and work well on either alternating current or direct current. As a result the incandescent lamp is widely used in household and commercial lighting, for portable lighting, such as table lamps, some car headlamps and electric flashlights, and for decorative and advertising lighting.

Some applications of the incandescent bulb make use of the heat generated, such as incubators (for hatching eggs), brooding boxes for young poultry, heat lights for reptile tanks, and the Easy-Bake Oven toy. In cold weather the heat shed by incandescent lamps contributes to building heating, but in hot climates lamp losses increase the energy used by air conditioning systems. Since in northern countries like those in Scandinavia there is little need for artificial lighting outside of the heating season, up to 50% of energy used annually in incandescent bulbs is used efficiently.

Incandescent light bulbs are gradually being replaced in many applications by (compact) fluorescent lights, high-intensity discharge lamps, LEDs, and other devices, which produce the same amount of visible light but use less electrical energy. Some jurisdictions have or are considering banning the sale of incandescent lightbulbs in favour of more energy-efficient lighting.