A bra (/ˈbrɑː/) (or brassiere UK /ˈbræzɪər/ or US /brəˈzɪər/) is a form-fitting undergarment that women wear to support their breasts. Women may also wear bras to conform to social norms or because they believe bras prevent breasts from sagging, a fact that even bra makers don't support. In western cultures, about 10-25% of women don't wear a bra, either as a matter of preference or sometimes for health or comfort reasons. In Third-world countries, women typically can't afford bras due to a lack of manufacturers and retailers.Women spend around US$16 billion a year on bras. Bras are a complex garment made of many parts, and manufacturers' standards and sizes vary widely worldwide. Their sizing systems and methods of bra-measurement vary to such an extent that even professional fitters can disagree on the correct size for the same woman. Manufacturers mass-produce bras as ready-to-wear garments and size them to fit standard, idealized, female torsos. Women's breasts may sag, vary in volume, width, height, shape, and position on the chest, and up to 25% of women's breasts are visibly asymmetrical. As a result, it can be difficult for women to find a bra that fits them correctly, and 80–85% of women wear an incorrectly sized bra.Changing social trends in some Western cultures allowing bras to be seen and novel materials have increased the variety of available designs. Some garments, such as swimsuits, camisoles, tank tops and backless dresses, have built-in breast support, alleviating the need to wear a separate bra. Manufacturers now make bras that in some instances are more fashionable than functional. Bras were originally designed with the primary function of supporting breasts but have become a fashion item with cultural significance. When a young girl gets her first bra, it may be seen as a rite of passage and symbolic of her coming of age. Some feminists consider bras a symbol of the repression of women's bodies.