Ever noticed the small pocket in the crotch of your underwear? That’s called a gusset (or crotch lining). It’s not extra fabric or a place for toilet paper—it’s there to add comfort and breathability. The gusset helps your underwear stay in place while allowing your body to breathe and protecting sensitive areas. It also helps wick moisture, reducing the risk of irritation, yeast, and bacteria.

Some fancy or sexy underwear may not have a gusset, as they’re often designed for short-term wear.