For example, when we pass sunlight through a prism, we see light of various colors. This is evidence that sunlight is a mixture of various colors. When the light is passed through a prism, the colors of the mixed light become visible separately.
Raindrops in the clouds above the sky perform the same function as prisms. These raindrops break up the sun's rays into several colors and produce a rainbow in the sky.
The colors are arranged in a certain way, with red on the outside and purple on the inside. However, sometimes the colors are arranged in the opposite order, so please be careful.
The reason why there are seven colors of rainbow is because the light of the sun, which is the source of rainbow, is made up of approximately seven different colors of light.