The Electromagnetic Spectrum is the complete range of electromagnetic waves placed in order of increasing frequency. In the example behind, the waves with the shortest wavelength, and thus the highest frequency, are placed at the left.
Radio Waves are electromagnetic waves that have the longest wavelength and the shortest frequency. Radio waves that have longer wavelengths are used to transmit information, while radio waves with shorter wavelengths are microwaves.
Microwaves are radio waves with the shortest wavelengths. Microwaves are used in ovens, radar and cellar communication.
Infrared Rays have a higher frequency than Radio waves, so they transfer more energy. You can feel this energy as heat. The picture in the back is a thermogram. that is a picture that sees Infrared Rays, or heat, instead of light.
Visible Light is the next sector on the Electromagnetic Spectrum. These are the waves that we can perceive, and we see them as light and color. The longer the wave, the brighter the color, going from red, to yellow, to green, to blue, finally ending with purple.
Next we have Ultraviolet Rays. They carry more energy than light, and can kill cells. A little exposure to Ultraviolet Rays is healthy because it causes cells to produce Vitamin D.
X-rays can penetrate through almost all matter, but cannot pass through dense matter, like bones. But, like Ultraviolet Rays, too much exposure will cause cancer.
Lastly, we have Gamma Rays. These rays are used to diagnose and treat cancer. Some nuclear reactions create Gamma Rays. Also, they are responsible for creating the fictional character Hulk.