Yoga pants built a $48 billion industry that's replacing jeans

The first pairs of yoga pants Lululemon sold in 1998 were a simple item for women to wear at the studio. They were a mix of nylon and Lycra—synthetic elastic fibers that provided the stretch and softness needed to manage all those sweat-inducing contortions during a lengthy session on the mat.

Yoga, first as an exercise and later as a cultural phenomenon (or cliché, depending on your cynicism), had yet to take hold. At the turn of the century, the pants filled a niche for yogis who were simply looking for a higher-end alternative to plain cotton leggings