<Ul> <Li> Main article: Electric arc <Ul> <Li> Arc lamp </Li> <Li> Flashtube </Li> </Ul> </Li> <Li> Main article: Electrostatic discharge <Ul> <Li> Lightning </Li> <Li> Electric spark </Li> </Ul> </Li> <Li> Main article: Gas discharge lamp <Ul> <Li> Electrodeless lamp </Li> <Li> Excimer lamp </Li> <Li> Fluorescent lamp <Ul> <Li> Compact fluorescent lamp </Li> <Li> Tanning lamp </Li> <Li> Black lights </Li> <Li> Geissler tube </Li> <Li> Moore tube (Defunct) </Li> <Li> "Ruhmkorff" lamp (Defunct) </Li> </Ul> </Li> <Li> High - intensity discharge lamp <Ul> <Li> Carbon arc lamp </Li> <Li> Ceramic discharge metal - halide lamp </Li> <Li> Hydrargyrum medium - arc iodide lamp </Li> <Li> Mercury - vapor lamp </Li> <Li> Metal - halide lamp </Li> <Li> Sodium - vapor lamp </Li> <Li> Sulfur lamp </Li> <Li> Xenon arc lamp </Li> </Ul> </Li> <Li> Hollow - cathode lamp </Li> <Li> Induction lighting <Ul> <Li> Sulfur lamp Sulfur lamps </Li> </Ul> </Li> <Li> Neon and argon lamps <Ul> <Li> Dekatron (Defunct) Dekatron </Li> <Li> Nixie tube </Li> </Ul> </Li> <Li> Plasma lamp </Li> <Li> Xenon flash lamp </Li> </Ul> </Li> </Ul> <Li> Main article: Electric arc <Ul> <Li> Arc lamp </Li> <Li> Flashtube </Li> </Ul> </Li> <Ul> <Li> Arc lamp </Li> <Li> Flashtube </Li> </Ul> <Li> Main article: Electrostatic discharge <Ul> <Li> Lightning </Li> <Li> Electric spark </Li> </Ul> </Li>

What are the most common sources of light