White light is made up of all the colors of light. Sunlight contains all the colors of light in a continuous spectrum. A prism may separate the colors and produce a rainbow.
Every color has its own wavelength. In the visual spectrum of light, the color violet has the longest wavelengths and lowest frequency, followed by blue. These colors travel the farthest; this is the reason mountains appear blue from a distance. Red is the highest frequency color, and it has the shortest wavelength of the visual spectrum. Visible light is only a small section of the full electromagnetic spectrum, which includes X-rays and radio waves as well.