I read that the corset was the 1st woman's undergarment ever that existed before bra and panties. I looked up corsets on google and they just basically looked like one piece underwear. It looks like only one piece underwear existed before the two piece bra and panties. Fun fact: Today, little girls wear ONLY one piece underwear until they're ready to wear a two piece underwear when their breasts start developing and/or when they're a certain age, when they're older they can still wear one piece underwear but by than most girls only wear two piece underwear.
Most Helpful Girl
One piece underwear isn't the same as a corset. The main distinguishing aspect is that a corset shapes the torso into a particular shape. Which is why someone like Dita Von Tease has a very tiny waist, because she wore corsets that basically molded her body. Although, these days there are tops referred to as corsets because they share the same look without the function. One piece underwear doesn't mold the body at all.3