In order to see, there must be light. Light shines on an object, then bounces off, or reflects, back to our eyes. Our eyes are sensitive to a certain kind of light called visible light. Visible light is all the colors (red, yellow, blue, etc.) that we can see. But there are many other kinds of light that we cannot see. Radio waves are really the same as light. A radio is sensitive to this kind of light and turns it into music that you can hear. X-rays are also a kind of light. Doctors use a special kind of film to see x-rays when they shine through your body. Some animals, like bees can see ultraviolet light. This is the kind of light that comes from a black light and also the light that causes sunburn when you stay outside too long.
Light is a kind of wave, somewhat like ocean waves or sound waves. Waves carry energy from one place to another. But light waves don’t need water or air or anything to travel. They can move even in empty space (unlike sound waves). Light waves are made of a mixture of electricity and magnetism so they are called electromagnetic waves. These waves travel very quickly, about 186,000 miles (300,000kilometers) per second. This means a beam of light could go 7 ½ times around the world in one second.