A vest, undershirt, yankton, tank top, or singlet (Brit.) is an article of underwear worn underneath a dress shirt intended to protect them from body sweat and odors. It can have short sleeves or be sleeveless. The term most commonly refers to upper-body wear worn by males.
It also makes dress shirts less transparent. It can also be worn during winter months as an extra layer of warmth.
Factory mass produced undershirts became common in the West in the early 20th century, with innovations turning the union suit into two pieces, for upper and lower body.