A hairpin is a small, U-shaped piece of wire or plastic used to hold hair in place. You push it into your hair so the two prongs grip from opposite sides, keeping a bun, braid, or twist secure. Unlike a hair tie that wraps around hair, a hairpin slides through it and locks it down.

If you look at a hairpin from the side, it looks like a narrow, upside-down U. This distinctive curve also appears in hairpin turns, those sharp, tight curves on mountain roads where drivers must slow way down and turn the steering wheel hard in one direction, then immediately hard in the other. Just like the wire doubles back on itself in a hairpin, the road doubles back on itself as it climbs or descends a steep slope.

Hairpins have been used for thousands of years. Ancient Romans made them from bone and metal, while Japanese women have long used decorative hairpins called kanzashi as part of traditional hairstyles. Today, most hairpins are simple and practical, though decorative ones with beads, flowers, or jewels are still popular for special occasions.