Light
Light with a wavelength shorter than violet is called ultraviolet light. X-rays and gamma rays are forms of light with even shorter wavelengths than ultraviolet. Light with a wavelength longer than red is called infrared light. Radio waves are a form of electromagnetic radiation with a wavelength longer than infrared light. The microwaves that are used to heat food in a microwave oven are also a form of electromagnetic radiation. Our eyes cannot see those kinds of energy, but there are some cameras that can see them. The various forms of light, both visible and invisible are the electromagnetic spectrum.