A fingerprint is the unique pattern of tiny ridges and swirls on the tip of each finger. If you press your thumb onto an ink pad and then onto paper, you'll see these patterns clearly: loops, whorls, and arches that form a design unlike anyone else's in the world.

No two people have identical fingerprints, not even identical twins. This makes fingerprints incredibly useful for identification. Police detectives dust crime scenes for fingerprints because a single print can prove who touched an object. Hospitals take babies' footprints at birth to ensure they never get mixed up with other newborns. Many phones now unlock when they recognize your fingerprint, which is more secure than a password because no one else has your exact pattern.

Scientists aren't completely sure why we have these ridges, though they probably help us grip objects better and feel textures more precisely. What's remarkable is that your fingerprints form before you're born and stay the same your entire life, even as your hands grow larger.

The word can also describe anything that serves as a unique identifier. A writer might have a distinctive fingerprint in their style, or a musician might leave their creative fingerprint on every song they compose.