How are rainbows formed?

A rainbow is created by the refraction of
sunlight by water droplets in the atmosphere.
When sunlight passes through a drop of water,
it is bent in such a way that the various colours
that make up white light are split. Each colour
is bent at different angles. Red bends the
least, while violet is bent the most. It is this
phenomenon that we see as a rainbow.

A rainbow of colours
The rainbow is always formed on that portion of the sky
that is directly opposite to the Sun. A rainbow is not
composed of just seven colours. In fact, it also contains
colours like infrared that cannot be seen.