The sun, stars, fires, candles, and electric light bulbs are all examples of light sources. They give off light that allows us to see objects around us. Visible light is a type of electromagnetic radiation detectable by the human eye with wavelengths between 380-740 nanometers. It travels at 299,792,458 meters per second in a vacuum and exhibits properties of both waves and particles. The study of light, called optics, is an important area of modern physics research.