The sun warms our planet every day, provides the light by which we see and is necessary for life on Earth. But what is it exactly, and what will happen when it burns itself out?| HowStuffWorks
Electricity completely surrounds us whether you're charging your cell phone or watching the sky light up during a violent thunderstorm. For most of us, modern life would be impossible without it, and the natural world relies on it.| HowStuffWorks
In its purest form, it's odorless, nearly colorless and tasteless. It's in your body, the food you eat and the beverages you drink. All forms of life need it. What substance is more necessary to our existence than any other? Water.| HowStuffWorks