Panties (in American English; also called underpants, undies, or knickers in British English) are a form of underwear worn traditionally by women. Panties can be form-fitting or loose. Typical components include an elastic waistband, a crotch panel to cover the genitalia (usually lined with absorbent material such as cotton), and a pair of leg openings that, like the waistband, are often made of elastomer. Various materials are used, but are usually chosen to be breathable.

Panties are made of a variety of materials, including cotton, lace, latex, leather, lycra, mesh, nylon, PVC, polyester, rawhide, satin, and silk. Construction typically consists of two pieces (front and rear) that are joined by seams at the crotch and sides; an additional gusset is often in the crotch, with the waistband and leg-openings made from elastomer.