Spandex is a synthetic fabric that can stretch to several times its normal size and then snap back to its original shape without losing its form. You've probably worn spandex without even thinking about it: it's woven into most athletic clothes, swimsuits, and even everyday jeans to help them move with your body.

Before spandex was invented in 1958, athletes wore stiff cotton uniforms that got heavy with sweat and restricted movement. Spandex changed sports forever because it stretches when you move and stays in place without bunching up or sagging. Swimmers wear suits with spandex to move through water more smoothly. Gymnasts need spandex in their leotards so they can flip and twist without their clothes shifting. Even astronauts wear spandex underlayers in their spacesuits.

Most clothing contains only a small percentage of spandex blended with other fibers like cotton or polyester. Pure spandex is so stretchy it would be difficult to wear, but mixing just 2% to 5% into other fabrics gives them flexibility and comfort while keeping their structure. That's why your favorite pair of jeans probably feels more comfortable than the stiff denim jeans your grandparents wore: a little bit of spandex makes a big difference.