Toplessness refers to the state in which a woman's breasts, including her areolas and nipples, are exposed, especially in a public place or in a visual medium. The male equivalent is known as barechestedness.

The breast is one of two prominences located on the upper ventral region of the torso among humans and other primates. Both sexes develop breasts from the same embryological tissues. The relative size and development of the breasts is a major secondary sex distinction between males and females.