Little ridges
Look closely at your fingertip. You'll see tiny raised lines curving across it. They're called ridges.
Ridges are on your palms, fingers, toes and the soles of your feet too. When you touch a glass or a mirror, sweat and oil on the ridges leave a copy behind. That copy is a fingerprint.
Scientists think the ridges help you feel tiny bumps and textures. As your finger slides over something, the ridges shake a little, and nerve endings feel it.
Ridges may also help your fingers grip some things, a bit like the bumps on the bottom of a sneaker.
Made before you were born
Your fingerprints started forming months before you were born, while you were still tiny and growing.
Once they formed, the pattern was set for life. As you grow, your prints get bigger, but the pattern stays the same.
If the top of a fingertip gets a small scrape, the ridges grow back in the very same pattern.
No two alike
No two people have ever been found with exactly the same fingerprints. Even your ten fingers each have their own print.
Identical twins have the same genes, but they still have different fingerprints. That's because tiny things, like how each baby moved and pressed while growing, shaped the ridges a little differently.
Because prints are one of a kind, people use them to unlock phones and to solve mysteries.
Loops, whorls and arches
Fingerprints come in three main patterns.
Loops curve around and head back out the same side they came in, like a hairpin. Loops are the most common pattern.
Whorls (WURLS) make circles or spirals, like a tiny whirlpool. Arches go up and over like a little hill. Arches are the least common.
Try it! Scribble with a pencil on paper, rub a fingertip on the scribble, then press clear tape on your fingertip and stick it on white paper. Which pattern do you have?