A bra, short for brassiere or brassière, is a form-fitting underwear that is primarily used to support and cover a woman's breasts. A typical bra consists of a chest band that wraps around the torso, supporting two breast cups that are held in place by shoulder straps. A bra usually fastens in the back, using a hook and eye fastener, although bras are available in a large range of styles and sizes, including front-fastening and backless designs. Some bras are designed for specific functions, such as nursing bras to facilitate breastfeeding or sports bras to minimize discomfort during exercise.