The World

Whether you keep it short and sweet or you're a spam champion, you've no doubt used e-mail. But how much do you really know about it? Take our quiz to find out!

Compact discs are a popular storage device for both music and computer files. But how much do you really know about them? Take our quiz to find out!

Without memory, computers wouldn't be able to store data in any way. How much do you know about computer memory?

Whether you know it or not, you probably use gears several times each day. Gears are used in a wide variety of mechanical devices including wrist watches, bathroom scales, washing machines and, of course, automobiles.

Digital cameras have helped make photography easier and faster for millions of people, but how much do you really know about them? Take our quiz to find out!

Hydraulic equipment is amazing in its strength and agility. From common backyard machines to the huge machines you see on construction sites, hydraulics make quick work of even the most difficult tasks. How much do you know about hydraulic machines?

Photography began as a curiosity but has evolved into one of the world's most popular hobbies. Find out how much you know about cameras by taking our quiz.

They may look similar from the outside. But there are many significant under-the-hood differences between an electric-powered car and a car that makes use of an internal combustion engine. How much do you know about electric cars?

Automobile ignition systems rely on perfect timing. A simple spark, when delivered at precisely the right moment, can mean the difference between a smoothly running, powerful engine that operates cleanly and an engine that runs rough, lacks power and produces unnecessary emissions. Let's get your motor running.

Catalytic converters are amazingly simple devices that have proven to be highly effective at reducing harmful emissions produced by car engines. How much do you know about catalytic converters?

Buying a car is often perceived to be a difficult and confusing process. If you take the time to learn what you need to know before purchasing a vehicle, the entire process is relatively simple and straightforward. So, how much do you know about buying a car?

What looks like a battery, has two terminals like a battery and stores electrons like a battery? Capacitors can store and release electrical energy, but don't replenish their supply. How do capacitors work, and what tools rely on them?

As the saying goes, home is where the heart is. But just how does one go about building a home in the first place? Find out some fun facts about this detailed process by taking the quiz.

The air and fuel mixtures that power your car's engine are controlled by valves that open and shut. The essential camshaft rotates and instigates the valve movement. But how exactly does this crucial engine part work? See how well you can shift mental gears and take the camshaft quiz.

The suspension of a car is actually part of the chassis, which comprises all of the important systems located beneath the car's body. Suspension systems have been smoothing out bumpy rides for centuries -- first in carriages, now in cars. How much do you know about car suspensions?

Imagine how convenient it would be if two-thirds of the Earth's surface was covered with a readily available, nonpolluting fuel source. With the discoveries being made in regards to salt water fuel, you may not have to imagine much longer. In 2003, John Kanzius serendipitously discovered a way to burn salt water. How would salt water fuel impact the world?

Do you remember when Web pages were in basic HTML and there was no such thing as online social networking? Things have changed fast, but do you know where the Web is going now? Take our Web 3.0 Quiz to learn about the future of web technology.

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?

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.

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?

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