For most of us, "workout underwear" is whatever we grab while packing a gym bag or whatever underwear we were wearing during the day. There's already so much other gear that you seemingly need to work out, so underwear is usually not top of mind.
But hear me out: Have you ever done Pilates wearing lace underwear and ended up with an imprint of the design on your butt? Or gone on a run and chafed so much it turned into a walk? Or taken an indoor cycling class and left with a sweat-soaked crotch? If the answer is yes to any of those, then you may want to consider getting workout-specific underwear.
Workout underwear can make exercising more comfortable, because it's often made from smooth, stretchy fabrics that wick away sweat and moisture — and that's important from a health standpoint, too. Bacteria and yeast that cause vaginal infections love hanging around warm, wet environments. So, wearing underwear that can manage moisture (and taking off your sweaty leggings and underwear once you're finished exercising) can help prevent vaginal infections.