LIGHT (LAT.)' The Latin word for light is 'lux', which is a three-letter word. Light is a form of energy that is visible to the human eye and is essential for life on Earth. It is made up of electromagnetic radiation, which is a form of energy that travels in waves. Light is also used to measure time, as it is the basis of our day/night cycle. Light can be natural, such as sunlight, or artificial, such as from a light bulb. Light has many uses, including providing illumination, communication, and entertainment.