Light refers to a type of energy that is radiated by moving charged particles that is visible to the human eye. The most prominent light source is the sun. Lights are known to act like particles at times, and like waves at other times. All matter is composed of atoms, which comprise of electrons. The action of electrons is known to emit light in most sources.

In a number of cases, energy from the sun, also known as solar energy, is used to create light. Solar energy does not prove sufficient at night, creating the need for electrical lighting. Today most of the world use electrical lights during the night and even for added lighting during the day. Electrical lights are powered by electric grids and may even have generator backup.

There are a variety of lights available in the market, including incandescent light bulbs and arc lamps. A wide range of gas discharge lamps are also available. These include fluorescent lights, neon lamps and modern photographic flashes. Laser lights, light-emitting diodes and sulfur lights are also available. Sulfur lights are used mostly for outdoor public lighting purposes.

Battery-powered lights in the form of flashlights and torches are also forms of light. These are portable and popular with travelers. Lamp is the common term used to refer to a light source.

The term watt is a unit of measurement of power. The amount of electrical power that it uses, determines the wattage of the lamp. The wattage also determines the brightness of a light. Since most lights are powered by electricity, people need to be careful while handling these devices. Most lamps and light fittings are not water resistant and exposure could lead to an electrical sock. If sparks are noticed on a light source, the electrical supply should be shut off in order to avoid short circuits.