G-string underwear is a very minimalist range of underwear.
The underwear is made by a small triangle of fabric that offers a strategic coverage but little else. This small triangle fabric is held in place by a very narrow strap or chain, which passes between the legs and is connected to another surrounding life. This underwear is usually marketed and worn by women, but the versions of the men, while less common there. This underwear style is usually worn under regular clothes, but it is also rarely encountered in the context of swimwear.