Back in the 17th century, physicist Isaac Newton (remember the falling apple? ) demonstrated that white light is made up of all colors of the visual spectrum by shining sunlight through a prism. When we shine white light through a prism, it's split into its component wavelengths, which we perceive as the colors of the visual spectrum, as illustrated below.

As you can see in the figure, when we shine white light through a prism, it's split into its component wavelengths, which we perceive as the colors of the visual spectrum.