The World

You can find batteries under the hood of your car, inside a TV remote -- even within hearing aids. Batteries were invented nearly two centuries ago, and they keep getting more sophisticated. But how well do you know what's at work inside these cans of chemicals?

Electric motors are inside all kinds of ordinary devices, using a power source to make motion. So what makes the motor go 'round?

Not long ago, most Americans associated tattoos with sailors, bikers and sideshow artists. But tattoos have become more popular in recent years. What does it take to get an image under your skin?

Wireless networks are easy to set up and inexpensive. They're also unobtrusive -- unless you're on the lookout for a place to use your laptop, you may not even notice when you're in a hotspot. But as you'll find out in this quiz, there's a lot more to them than meets the eye.