Girls are generally born with a thin membrane that covers the vagina opening. This is called a hymen. Intact hymens vary widely in shape from woman to woman. For most women, the hymen stretches easily, but even after being stretched, little folds of hymen tissue remain (below, right).

Though it was long believed the absence of a hymen meant sexual intercourse had occurred (i.e., the woman was not a virgin), this is not necessarily true. The hymen is a delicate piece of skin that can stretch and break from sexual intercourse, the use of a tampon, or even vigorous exercise.The stretching and tearing of the hymen is what causes bleeding to sometimes occur after intercourse. “Popped her cherry” is a slang term describing the breaking of the hymen.