The World

Without web servers, there wouldn't be an Internet. Do you know how web servers work to get you online? Take this quiz and find out.

It wakes you up, gets you going, and may even cure your headache. But how much do you really know about caffeine?

If you've ever walked into a new friend's home and felt that you'd been there before, then you've experienced déjà vu. If you've ever walked into a new friend's home and felt that you'd been there before, then you've experienced déjà vu. If you've ever ... OK, that's enough. Is it reincarnation? Is something wrong with the brain? What's behind this eerie feeling?

MP3 players have replaced the Walkman and Discman as a portable audio device. Do you know how they work? Take our quiz to find out.

Booze, hooch, devil's brew. Whatever name you call it, alcohol is really just a combination of carbon, hydrogen and oxygen molecules. Test your knowledge of this simple compound with our quiz!

Think you know everything about the mafia and organized crime? Test your knowledge of the mafia with our mafia quiz.

When did countries start using lethal chemical concoctions and hazardous viruses, bacteria and toxins as weapons? Where do they come from? You're about to enter the world of biological and chemical warfare.

If there's one clear message Sen. Barack Obama wants to get across to the voters, it's that he represents change. He also wants America to know that he's the candidate who can unite the U.S. government. So how will he do it if he's elected president?

It can be a sign of love, grief or respect worldwide. Kissing is a natural act that gives millions of people physical and psychological satisfaction, but where did it originate? Why does it make us feel good?

Spies can have fake wives, fake degrees, fake interests and fake lives. Spies are often romanticized in Hollywood, but how does James Bond compare with real spies? And what happens when a spy is spying on the people he's supposedly spying for?

Skydiving has been described as one of the greatest adrenaline rushes a human being can have. So what keeps skydivers safe as they plummet to Earth? And what happens if something goes wrong on your jump?

How much do you know about competitive eating contests? Quiz yourself and learn more about competitive eating.

They are the most notorious species of shark, boasting 3,000 jagged teeth and a bite that kills. See how much you know with this quiz.

Tiger sharks have been known to eat everything from deer antlers to explosives to a suit of armor. What makes them so willing to eat anything? And how do they compare to their fellow seafaring predators?

Many shark attacks, while deadly, are mistakes. So why do sharks attack humans? And how can you avoid being mistaken for prey next time you're at the beach?

Astronauts have a reputation for being the brave and skilled few willing to risk their lives by strapping themselves aboard a rocket and blasting into outer space. How much do you know about this dangerous job?

Since the 19th century, humans have wondered about the prospect of life on Mars. While we haven't sent anyone to the Martian surface, we have sent spacecrafts, which have gathered a good amount of information on what it's like on Mars. How is it different from Earth? How is it similar? And could life really have existed there long ago, or exist in the future?

At its best, the space shuttle is the embodiment of 20th-century scientific progress. At its worst, the shuttle is a symbol of the dangers that come with space travel. Take this quiz to see how much you know about the space shuttle program.

By Maria Trimarchi

How much to you know about this financial capital of the world? Take our Dubai quiz to test your knowledge and learn about lesser-known aspects of Dubai's culture.

They are notoriously savage and bloody when they attack, but behind a sharks' vicious reputation is a variety of different shapes, sizes and demeanors. Learn all about the different types of sharks.

Lurking in southern swamps from the Carolinas to Louisiana, alligators' place in folklore is both well-established and well-deserved. Get too close to one, and you'll find that their predatory abilities are no tall tale. What makes them so dangerous?

Meerkats aren't your typical cute, furry rodents. These desert dwellers are members of close-knit communities where everyone pitches in to look out for predators and teach the young. When they aren't looking for a bite to eat or grooming each other's fur, however, meerkats can be lethally competitive. What is it about these African critters that leaves us so enthralled?

Wolves supposedly howl at it, a fairy tale claims a cow once jumped over it and legends say if you look hard enough, there's a man in it. Yes, the moon has a prominent place in popular culture, but there's a lot you might not know about Earth's little orbiting friend. Why doesn't it have soil? Why is its gravity so important? And are we really thinking of going back soon?

A famous slogan claims that a diamond is forever. While these precious stones symbolize love and glamour for millions of couples, there's a lot about nature's most famous jewel you might not know.

An MRI machine is more than just a big, claustrophobia-inducing tube. How much do you know about what's going on inside -- or what's going on inside your body while you're in there?