The take-home message here is that the electromagnetic spectrum is characterized by radiation of different wavelengths. Each color that we see in a rainbow represents one particular wavelength of light, such as blue light which has a wavelength of approximately 480 nm. FM radio and TV signals have a wavelength about the height of an average person. Maybe that's why we spend so much time paying attention to these signals. Let's take a closer look at visible light.
Visible light occupies only a small part of the electromagnetic spectrum.
We are able to see visible light because our eyes are only sensitive to visible light. That's why it's called visible light. But if we had eyes like hydrothermal vent shrimp, we would be able to see the heat patterns radiating from our fellow students and the food down at the cafeteria. Returning to rainbows, we notice that there is a pattern to the colors which occur. The long wavelengths of visible light are red and orange.