The breasts are two protruding, milk-producing glands, which are located on the front of the chest. Male breasts are an undeveloped version of those on the female. Each breast is divided into fifteen to twenty lobes that radiate inward from the nipple and hold small clusters of milk-producing glands that have ducts which open out at the nipple of the breast for breast feeding new-born babies. 

The primary function of the breast is to nourish a baby, but from ancient times, it has also been a symbol of femininity, beauty and eroticism. The size and shape of the female breasts probably differ more than any other part of the body. These not only differ in individuals but at separate phases of a woman's life - during pregnancy, during the menstrual cycle, and after menopause. 

The breasts are really modified sweat glands, which are made up of fibrous tissues and fat that provide support and contain nerves, blood vessels and lymphatic vessels. The darker pigment around the nipples are called, "areola," and the nipples themselves become erect because of cold, breast feeding or during sexual activity. 

The size of the breast cannot be increased by exercise because there are no muscles within it, but only ligaments which interlace the fat and tissue. The amount of milk is not dependent upon the size of the breast (which is set by genetic heritage.) The red, irritation of "jogger's nipples," as well as strain and stress of tissues leading to "sagging" breasts, can be corrected by wearing a good, supportive bra.