They are primarily made from cotton and linen. Tiny colored fibers are added for security. What are they?

Despite its common name, the currency in your wallet isn't made from trees at all. Instead, it’s a specialized blend of approximately 75% cotton and 25% linen, giving it a unique, fabric-like feel. This composition is what makes a bill so durable. It can survive accidental trips through the washing machine and withstand thousands of folds without tearing, a feat that typical wood-pulp paper could never accomplish. This resilience is essential for an object that changes hands so frequently over its lifespan.

The tiny red and blue fibers scattered throughout the bill are one of its oldest and most effective security features. Rather than being printed on the surface, these threads are physically embedded within the material during the manufacturing process. This makes them incredibly difficult for counterfeiters to accurately replicate. These fibers work in tandem with other modern security measures, such as embedded security threads that glow under UV light and subtle watermarks, all designed to protect the currency's integrity and maintain public trust.