Millions of women reach for one every day, but how much do they really know about their most intimate apparel? Throughout history, undergarments have shaped women's bodies to reflect the social expectations of the time. Nowhere is this more apparent than with the bra. From boiling cauldrons to silk looms to metal factories, this special traces the evolution of one of woman's most provocative pieces of clothing.

Delicate fabric, exquisite details and curve-hugging cups make the bra an ultimate symbol of femininity, but behind the fragile exterior lies tough design, grueling construction and complicated science. Some of the facts and figures revealed in the special include the following:

• Caterpillar spit, dirt, crude oil and molten metal are several of the ingredients in a bra.
• There are over 40 components of a bra.
• Over 4 million new bras are created on average every day.
• Each woman owns an average of six and a half bras.
• In the last 15 years, the average bust size has increased from 34B to 36C.
• The modern system of bra sizing was invented in 1928.
• How many ounces in a cup? An A cup -- approximately 8 fluid ounces; B cup -- 13 ounces; C cup -- 21 ounces; and D cup -- 27 ounces.
• Women's breasts can range from 10 ounces to 20 pounds, and a 1.6-ounce bra has to support all shapes and sizes in between.
• Consumers spend around $16 billion a year on bras.