An electromagnetic wave is a type of energy that travels through space at the speed of light, carrying no mass and needing no medium to move through. These waves are created when electric and magnetic fields vibrate together, sending energy outward like ripples spreading across a pond, except these ripples can travel through the vacuum of space.

Electromagnetic waves include many types of energy you encounter daily. Radio waves carry music to your car stereo. Microwaves heat your food. Visible light lets you see colors and read this page. X-rays help doctors see inside your body. Ultraviolet light from the sun can give you a sunburn. These are all electromagnetic waves, differing mainly in their wavelength, which is the distance between wave crests.

Think of wavelength like the difference between ocean waves: some are tiny ripples close together, others are massive swells far apart. Radio waves have long wavelengths (some stretch for miles), while X-rays have wavelengths smaller than an atom. Visible light sits somewhere in the middle, with red light having longer wavelengths than blue light.

The remarkable thing about electromagnetic waves is their speed: all of them travel at about 186,000 miles per second in empty space. This means light from the sun takes about eight minutes to reach Earth, and radio signals sent to distant spacecraft can take hours or even years to arrive. Understanding electromagnetic waves helped scientists develop radio, television, radar, wireless internet, and countless technologies that shape modern life.