Number 1: the loop on the back of your shirt.

Most people look at the loop on the back of their shirt and wonder what it's for.

There is a purpose for it on the back of your shirt; there are actually three documented reasons and it's unknown which is correct.

The first is the most obvious: It's a way to hang your shirt on a hook.

This doesn't make sense, however, because if you hang your shirt on a hook by that loop, it will become wrinkled quickly.

The second could be a way to help you fasten your tie easier.

The last purpose is more romantic.

Years ago, American university students were said to have removed the loop from the shirt when they started dating a girl exclusively.

To show she was taken, the girl would wear a scarf with the university's emblem.

Number 2: the cylinder on your laptop's power cable.

Most people see the cylinder on their laptop's power cable every day and have no idea what it's for; some believe that it's for decoration.

It's called a ferrite bead, and it suppresses high frequency noise in the electrical circuits.

The design is quite simple; it's made from ferrite, and it's wrapped to protect it.

Number 3: the tiny hole in the window of a plane.

Airplane windows are made up of two pieces of perspex, which is plastic glass.

Without the tiny hole in the window, the inner piece of glass would shatter due to the difference in pressure between the plane's cabin and the outside.

The tiny hole lets air move from the cabin into the other pane of glass; the tiny hole equalizes the pressure between the two panes.

It's what keeps the cabin of the plane safe.

For such a tiny little detail, it has a huge lifesaving purpose.

Number 4: the blue part of the eraser.

Most people think that the pink part of the eraser is for pencil marks, and the blue part is for pen marks.

This is not true.

When you erase your pencil marks with the pink part, it's not uncommon for some pencil smudge to be left behind.

The blue part is designed to remove any of the pencil smudges.

When the eraser producers realized that people didn't understand the true reason for the blue part of the eraser, they started marketing it to remove pen marks.

Many erasers even have a picture of a pen printed on the blue part of the eraser, even though that was not its original purpose.

Number 5: the extra eyelets on your sneakers.

Most people believe that the extra eyelets on their sneakers are just there for decoration. This is false.

The extra eyelets are designed to fix the shoes in place so that they don't rub against your ankles when you are running or playing sports.

If you start using them, you might notice a big difference, especially if you're wearing ankle socks.

The extra eyelets also give you more stability in your ankles.

Number 6: the hole in a spaghetti spoon.

All spaghetti spoons have a hole in the bottom; some people believe it is so the water drains when you are stirring the spaghetti.

The actual purpose is to measure out an accurate amount of spaghetti for one serving.

While people often eat different amounts of spaghetti, the amount that fits in the hole is considered one serving.

Number 7: the little pocket within the big pocket on your jeans.

This is one of the most common things that you probably don't know what it is.

Most people think that the small pocket of the jeans is just for decoration.

The little pocket actually served a purpose a few years ago.

The first time the little pocket was seen was on Levi's jeans back in 1873.

Back then, pocket watches were very popular, and the small pocket was designed to hold the watch.

Today, since people don't really carry pocket watches anymore, the little pockets really don't have much of a purpose.

Number 8: the extra scrap of material that comes with new clothes.

Many people believe that the extra scrap material is to patch the article of clothing if it rips or to replace a button. This is not true.

The actual reason that clothing manufacturers add the scraps of material is so that you could wash it first.

This will let you see how the laundry detergent and the washing cycle will affect the clothing.

This will save you from ever fading or shrinking an outfit the first time you wash it.

Number 9: the hole in the top of a pen cap.

People believe that the hole at the top of the pen cap will allow air to get into their lungs if they accidentally swallowed the cap.

If you were to swallow anything, and it gets stuck in your trachea, the mucous membranes will start to swell.

The hole in the cap will keep it from becoming absorbed in the membrane.

Number 10: the snap on your pockets of your jeans.

The snaps on the pockets are not called snaps; they're called rivets.

A great deal of fabric is gathered and stitched at the pockets.

This area needs more strength due to the extra stitching, and the rivets will give the pocket more strength, preventing it from tearing.

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