A rainbow is an optical phenomenon and a visible spectrum of light caused by the refraction and reflection of sunlight through spherical water droplets suspended in the atmosphere. The underlying physical process involves the scattering of electromagnetic radiation, where incoming sunlight strikes the water particles. The light disperses—separating into its constituent wavelengths—as it enters the droplets, a process known as refraction. The light then reflects off the inner surface of the droplets and refracts a second time upon exiting, projecting the separated colors to the observer. The resulting arc is a geometric feature determined by the angle at which the incident light and the observer are positioned relative to the water medium. The observed colors follow a consistent order, generally ranging from red on the outer edge to violet on the inner edge, with the specific arrangement governed by the varying refractive indices of different wavelengths of light.