The term electromagnetic wave tends to bring to mind the waves emitted from cellular telephones, but electromagnetic waves are actually waves produced by electricity and magnetism.
Electromagnetic waves always occur wherever electricity is flowing or radio waves are flying about.

Maxwell's equations, which clearly revealed the existence of such electromagnetic waves, were announced in 1861, becoming the most fundamental law of electromagnetics. These equations are not easy to understand, but let's take an in-depth look because they concern the true nature of light.