The Hymen is a covering over the entry to the vagina, which is usually broken during initial intercourse. Many girls refer to this hymen as their "virginity", although being a virgin is a lack of sexual intercourse, and not a strictly physical thing. Some girls do not have a hymen, other damage or break it during sports, riding a bicycle, or sometimes even intention (or accidentily) as they learn about masturbation during their developing years.
Hymen from Wikipedia
The hymen (or maidenhead; or in slang cherry) is a fold of mucous membrane which surrounds or partially covers the external vaginal opening. It forms part of the vulva, or external genitalia, and is present in all females at birth. The most common formation of the hymen is crescentic or crescent-shaped, although several other formations are possible. A woman's hymen is destroyed when she gives birth; she may be left with remnants called carunculae mytriformes or the hymen may be completely absent.
The hymen has no known anatomical function. In societies which value chastity, the greatest significance of the hymen is a traditional belief that an intact hymen indicates a state of intact virginity. However, it is not possible to confirm that a woman or post-pubescent girl is a virgin by examining the hymen. A physician routinely checks the appearance of the hymen of baby girls at birth, and again during all future pelvic examinations. In cases of suspected rape or sexual abuse a detailed examination of the hymen may be carried out, however the condition of the hymen alone is often inconclusive or open to misinterpretation, especially if the patient has reached puberty.
The name hymen is from the Greek for membrane. Hymen is also a name for the Greek God of marriage and weddings, Hymenaeus, but this name has a different root.
Hymen. (2006, October 23). In Wikipedia, The Free Encyclopedia. Retrieved 19:56, October 24, 2006, from http://en.wikipedia.org/w/index.php?title=Hymen&oldid=83108476