What are the four basic types of lighting?
Incandescent – the most common type of lighting in the home; the familiar light bulb Thomas Edison perfected as a practical, commercially viable lighting system.
Fluorescent – used most commonly in commercial settings and which is much more efficient than the incandescent lamp; gas discharge lighting in the USA emerged commercially in 1938 and by 1951 overtook, in terms of total light output, incandescent lighting.
High-intensity discharge — which includes Mercury Vapor, Metal Halide, High Pressure Sodium (HPS) and Low Pressure sodium.
Light Emitting Diode (LED) — which is a relatively new and still expensive option, but the prices are slowly becoming competitive.