Do you love it when the circus comes to town? The big top…the exotic animals…the fun games…the cotton candy…what's not to like, right? If you're a fan of the circus, then there's probably one unique show you probably look forward to: the acrobats!

Poised high in the air, acrobats swing on trapezes, completing daring flips in mid-air. Even more impressive, however, is when the acrobats grab long poles and take a death-defying walk along a taut tightrope. How do they keep from falling?

Tightrope walking — also known as funambulism — has a long and storied history. The practice dates back to the ancient Greeks. In fact, the name "funambulism" comes from the ancient Greek words funis, meaning rope, and ambulare, meaning to walk.

No one knows for sure how the practice of walking across a rope or wire strung tautly between two points got started, but it's been a popular form of entertainment for centuries, especially at the circus. While the thought of tightrope walking might seem impossible to many, acrobats make it look easy, even doing tricks as they cross the rope.

Others have taken tightrope walking to new heights — literally. Highwire stunts feature tightropes stretched high in the air across chasms between buildings or across deep canyons. Although these feats are amazing, they're also very dangerous.

Tightrope walking requires extensive training. Some tightrope walkers wear special shoes made of cloth or flexible leather that allow them to bend their feet around the tightrope for increased security. Some even go barefoot so their toes can grip the rope.

The most important physical skill in tightrope walking is balance. To successfully cross a tightrope without falling requires walkers to keep their center of gravity directly above the rope.

You might have had some experience with this if you've ever tried to walk across a log over a stream or a thin beam, such as a balance beam. As you carefully balanced yourself, you may have bent your knees and put your hands out to your sides.

Doing so moved your center of gravity, which is normally just below the ribcage, closer to your feet, allowing you to balance more easily. Tightrope walkers do the same thing. If you've ever watched a tightrope walker in action, you will likely see them bend their knees and put their hands out to improve balance.

Many tightrope walkers also carry a long pole. This is basically like holding your arms out to your sides, except that the ends of the pole are like really long arms. The ends of the pole bend downward, helping to lower your center of gravity even farther.

Having your arms out to your sides or carrying a long pole also helps to distribute your mass evenly, which helps your body to fight rotational forces. As you walk on a tightrope, the rope will tend to twist or rotate. This rotation can cause you to slip, but extending your arms horizontally or carrying a long pole gives you time to make slight adjustments to counter rotation and prevent a fall.