Stays were the corsets worn by women in the 18th century. They were worn from infancy and were made of thick linnen onto which long, thin pieces of cane or whalebone were sewn vertically. This made the garment very rigid. The stays would end in a point, just above the abdomen and would be laced up at the back as tightly as possible. The garment was so tight around the waist and rib-cage, that movement and breathing was made difficult. (This explains why women fainted so easily..)
Stays would be worn over a white shirt-like garment, which was usually almost knee-length, (knickers had not been invented yet) and the skirt would be fitten under the bottom part of the stays, with the pointed part on the outside. The front panel was meant to be seen and so was often beautifully embroidered and colourfull. Over the skirt, another shirt-like garment would be worn, which would be open in front so you could see the panel and it would be tied to the stays with silk ribbons or just pinned on. This over- shirt would be the same colour and fabric as the skirt and it's hem reached the floor.
At dinner-parties and society events, it was quite common for ladies to pull their stays lower, so as to reveal as much as possible of their bosoms (and believe me, that must have been alot because in their normal position the stays almost revealed the nipple). In those days showing your 'tits' was clearly not scandalous but showing your ankles could have you removed from polite society! Times do change, don't they.