Briefs are close-fitting panties; the term is applied to both men's and women's garments.
Men's white briefs are sometimes called tighty-whities.
A well-known make of briefs for men is Jockey Y-Fronts, so called because the fly looks like an inverted Y.
Briefs for women come in various shapes and degrees of coverage, ranging from full briefs that come up to the waist and completely cover the buttocks, through bikini briefs and tangas to thongs. They are generally made of cotton, but silk and satin ones are available. They are available in a wide range of colours, often with patterns, frills and ribbon trimmings.
Particularly close-fitting briefs are sometimes called slips; slips for men usually lack flies.