Explain to me what a rainbow actually is?

A rainbow is an optical phenomenon that can occur under certain meteorological conditions. It is caused by reflection, refraction and dispersion of light in water droplets resulting in an effect similar to a spectrum of light appearing in the sky. It takes the form of a multicolored circular arc. Rainbows caused by sunlight always appear in the section of sky directly opposite the Sun.

A rainbow is an optical phenomenon that occurs by sunlight appearing in the section of the sky directly opposite of the sun.