Sun tanning or tanning is the process whereby skin color is darkened or tanned. It is most often a result of exposure to ultraviolet (UV) radiation from sunlight or from artificial sources, such as a tanning lamp found in indoor tanning beds. People who deliberately tan their skin by exposure to the sun engage in a passive recreational activity of sun bathing. Some people use chemical products that can produce a tanning effect without exposure to ultraviolet radiation, known as sunless tanning.

A bikini is a two-piece swimsuit primarily worn by girls and women that features one piece on top that covers the breasts, and a second piece on the bottom: the front covering the pelvis but usually exposing the navel, and the back generally covering the intergluteal cleft and a little, some, or all of the buttocks. The size of the top and bottom can vary, from bikinis that offer full coverage of the breasts, pelvis, and buttocks, to more revealing designs with a thong or G-string bottom that covers only the mons pubis, but exposes the buttocks, and a top that covers only the areolae. Bikini bottoms covering about half the buttocks may be described as "Brazilian-cut".