It might also refer to the upper forward surface of the human body, male or female, extending from the neck to the abdomen.
Although both human male and female breasts have mammary glands, the breast can been viewed as an organ designed to produce milk. Within the mammary gland is a complex network of branching ducts, or tubes, which link sac-like structures called lobules, which can produce milk in females, on out of the body through the breast's nipple.
It is composed largely of fat and the lobules and ducts are supported in the breast by surrounding fatty tissue and ligaments. There are no muscles in the breast. In tying breasts around in such a manner that they are being forced away from the body, these tissues and ligaments can easily be damaged; since they do not repair readily, this will cause the breast to sag and in severe circumstances can require surgery to re-attach (or replace) the breast.
The pigmented area around the nipple is called the areola.
Although the primary biologic function of the breast is to make milk to feed a baby, the breast is also a symbol of femininity and beauty. The appearance of the normal female breast differs greatly between individuals and at different times during a woman's life -- before, during and after adolescence, during pregnancy, during the menstrual cycle, and after menopause.
There is a great variety in the size, shape and comparative placement of breasts in women. Factors that affect this, especially size, include race, weight, eating habits, exercise and age. It is quite normal for a woman's breasts to be different sizes, with the left one typically being slightly larger.
Women can be insecure about their breasts, and it is not uncommon for women who are unhappy with their size to seek surgery to reduce or enlarge their breasts artificially, even though many men actually state a preference for medium-sized and most men state they prefer natural of any shape and size to false.
The size of a woman's breasts is typically expressed as a 'bra size'. Statistics published in the Journal for Sex Research in 1987 revealed that the female population (in USA) had the following bra cup sizes: A- 15%, B- 44%, C- 28%, D- 10%. According to the results of the 'Size UK' survey, the average bra size in the UK has increased from a 34B in the 1950s to a 36C in 2005 (though the average women is also more overweight, which increases breast size).
Bra cup sizes around the world are the same for the majority of women but there are some differences as the following table indicates:
|Cup sizes around the world|
|UK||USA||Most of Europe||France||Italy||Australia|
|B||B||B||B||B (or unlabelled)||B|
|E||DDD or E||F||F||E||-|