Why different colors appear in rainbow?

Different colors appear in a rainbow due to the dispersion of sunlight as it passes through water droplets in the atmosphere. When light enters a droplet, it bends (refracts) and separates into its component colors—red, orange, yellow, green, blue, indigo, and violet—because each color has a different wavelength and bends at a slightly different angle. This separation creates a circular spectrum of colors that we perceive as a rainbow. The result is a beautiful arc of colors that can be seen when the conditions are right, such as after rain with sunlight shining from behind.