Electromagnetic waves or EM waves are waves that are created as a result of vibrations between an electric field and a magnetic field. In other words, EM waves are composed of oscillating magnetic and electric fields.
Electromagnetic waves can travel through anything - be it air, a solid material or a vacuum. They do not necessarily need a medium to propagate or travel from one place to another.
EM waves are "transverse waves." This means that the electric and magnetic fields of an electromagnetic wave are perpendicular to each other and to the direction of the propagating EM wave. The course of EM waves are not deflected by either the surrounding electric or magnetic fields.
The Electromagnetic Spectrum
When you watch TV, scroll your IG feed, listen to the radio, or warm up your dinner in the microwave, you are using electromagnetic waves.
Radio waves and microwaves are two of seven types of electromagnetic waves. EM waves only differ from each other in wavelength and frequency.
The range of wavelengths or frequencies over which EM waves extend is known as the electromagnetic spectrum. Waves in the electromagnetic spectrum vary in size from very long radio waves the size of buildings, to very short gamma-rays smaller than the size of the nucleus of an atom!
The electromagnetic spectrum includes, from longest wavelength to shortest, or lowest frequency to highest: radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma-rays.
Of note, the human eye can only detect wavelengths from 380 to 700 nanometers. Waves outside of this range can not be seen because they are outside of the "visible light" spectrum.