Why/How do we see a rainbow?

Question

Why/How do we see a rainbow?

Answer 1

Rainbows can be observed whenever there are water drops in the air and sunlight shining from behind a person at a low altitude angle (on the ground). The most spectacular rainbow displays happen when half of the sky is still dark with draining clouds and the observer is at a spot with clear sky in the direction of the Sun. The result is a luminous rainbow that contrasts with the darkened background.

Answer 2

we see a rainbow because the way the sunlight refracts through the water droplets creates the beautiful colors