You heard about the myths ...now here are some facts!

1. Your vagina formed four months before you were born. All fetuses have genital tissue that develops into either male or female sex organs. At about 10 weeks, if DNA has destined the baby to be a boy, a penis and testes take shape. "If it's female, a vagina starts to form," says Susan Kellogg, Ph.D., director of sexual medicine at the Pelvic and Sexual Health Institute of Philadelphia.

2. Not all vaginas come sealed. If you didn't bleed when you lost your virginity, you may have broken your hymen - the thin swatch of tissue that normally covers the vaginal opening - while playing sports or putting in a tampon...or you may have been born without one. On the other hand, some women are born with a hymen so thick that it has to be surgically removed by a doctor before the woman can have intercourse and use a tampon.

3. It's only one part of your pubes. Many chicks think vagina refers to their entire pubic area. "Though your clitoris, outer labia and urethra are within an inch of one another, they are distinct body parts," explains Elizabeth Gunther Stewart, M.D., director of the Vulvovaginal Specialty Service in Boston and author of The V Book.

So what exactly is the vagina? It's the moist, muscular tube that begins at your inner lips and extends about three inches into your pelvis, ending at your cervix (the narrow opening to your uterus). Its purpose is to bring you sexual pleasure, allow you to menstruate...and serve as an exit strategy for a baby.

4. The first inch is the most sensitive. Although the upper two-thirds is an intense erogenous zone, it's not nearly as pleasure-receptive as the opening inch. "This is where the most nerve endings are," explains Patti Britton, Ph.D., a clinical sexologist in Los Angeles.

5. Getting busy is good for it. Whether you're knocking boots with your guy or flying solo, sexual stimulation keeps your vagina happy and more healthy. "Flexing your love muscles maintains tightness and tone," says Britton. "Also, the more moist your tissues are from lubricating when aroused, the less likely they are to become irritated."