How do light create a rainbow?

A rainbow is formed when light, typically sunlight, passes through water droplets in the atmosphere. As the light enters a droplet, it refracts or bends, then reflects off the inside surface, and finally refracts again as it exits the droplet. This process separates the light into its constituent colors due to different wavelengths bending at different angles, creating a spectrum that appears as a circular arc in the sky. The result is the vibrant array of colors that we see in a rainbow.