Sources of light are things or devices that produce light, and the two general sources are natural and artificial. The sun is Earth’s main source of natural light that releases its energy as heat and light. This light is known as white light, and it is what gives Earth daylight. Other forms of natural light include other stars, the moon, lightning, aurorae and noctilucent clouds.
Artificial sources of light are those created by humans. These include electricity and fire. For centuries, humans created light by burning wood, gas or oil, and through illumination devices such as candles and gas lamps. The most convenient and commonly used artificial light is electricity. The different types of electric lights include tungsten filament bulbs, fluorescent tubes, incandescent light bulbs, lasers and neon lights.
Light is a form of energy that is visible to the human eye. Light travels in waves, usually in straight lines called rays of light. Every wave of light has different wavelengths, which form different colors of light. Rays of light may change direction, bounce off and change speed depending on the type of material they are passing through. One known fact about light is that its speed cannot be matched by anything in the universe.