Light

 Light is a form of electromagnetic radiation that can be perceived by the human eye.  It is made up of particles called photons that travel in waves at a constant speed of approximately 299,792,458 meters per second or about 186,282 miles per second.  Light can be produced by a variety of sources, including natural sources like the sun, stars, and fire, as well as artificial sources like light bulbs, LEDs, and lasers.  It can be absorbed, reflected, refracted, or diffracted by different materials, depending on their properties.

Light can also be described in terms of its properties, such as its wavelength (the distance between two peaks or troughs of a wave), frequency (the number of waves that pass a given point per unit time), and intensity (the amount of energy carried by the light wave per unit area).  These properties determine how light interacts with other objects and how it appears to the human eye.

The study of light and its properties is known as optics, and has a wide range of applications in fields such as astronomy, physics, chemistry, engineering, and medicine.