Electromagnetic waves are waves that contain an electric field and a magnetic field and carry energy. They travel at the speed of light.
Quantum mechanics developed from the study of electromagnetic waves, which include visible light seen in the colors of the rainbow, but also other waves including the more energetic and higher frequency waves like ultraviolet light, x-rays, and gamma rays plus the waves with longer wavelengths including infrared waves, microwaves and radio waves.
Some types of electromagnetic radiation, such as X-rays, are ionizing radiation and can be harmful to your body. Ultraviolet rays are near the violet end of the light spectrum and infrared are near the red end. Infrared rays are heat rays and ultraviolet rays cause sunburn.
The various parts of the electromagnetic spectrum differ in wavelength, frequency and quantum energy.
Sound waves are not electromagnetic waves but waves of pressure in air, water or any other substance.

License information: CC BY-SA 3.0 and GFDL
MPAA: G
Go to source: https://simple.wikipedia.org/wiki/Electromagnetic_radiation