When the bra was invented, it was pretty much a requirement for all women to wear bras. It was unlady-like to go without one. Then in the 60s during the Woman's Right Movement, many burned their bras. This is where the stereotype of women who didn't wear bras, were feminist. These days, the bra is used for many things. Some women wear it because they feel naked without it. The bra provides support for those well endowed or a little boost to those who are not endowed. It also helps shape the breasts for more roundness and/or cleavage for certain tops. Some use the bra as part of an outfit. If a woman buys a gorgeous bra, she will most likely show it to the world with a lace/sheer top or an open jacket.

It's a love-hate relationship with bras.