What causes a rainbow to form?

A rainbow forms when sunlight is refracted, or bent, as it passes through water droplets in the atmosphere. The sunlight is separated into its component colors (red, orange, yellow, green, blue, indigo, violet) as it travels through the droplet and is reflected off the inside surface before exiting. The different colors of light bend by varying amounts, creating a spectrum of colors. Rainbows are most commonly seen when the sun is low in the sky, with rain or water droplets in the opposite direction.