Anatomy and Function
The hymen is a thin membrane which partially covers the external vaginal opening. It differs from woman to woman, and has various shapes; there are ring-shaped, crescent-shaped, fringed or tooth-shaped hymen.  [1] [2] [3]

The knowledge about all different shapes of hymen hasn't found its way into medical practice but in the eyes of the law, the medical opinion is considered evidence. [3]

In fact, the hymen is like an elastic band or annulus which surrounds the vaginal opening and can vary in size. Only in 46%, the hymen ruptures after first vaginal intercourse, in all remaining cases it completely extends during childbirth. It can neither be injured in sports like horse riding or cycling nor when introducing a tampon. [3]

Only in rare cases, when the hymen totally covers the vaginal opening, it has to be surgically removed because otherwise menstrual blood is blocked. [3]

In order to get rid of the word "mödomshinna" (literal translation: "maiden membrane") Swedish language introduced the term "slidkrans" (literal translation: "vaginal corona") in 2009 in order to avoid the twofold misunderstanding. On the one hand, the hymen is not a membrane and on the other hand it bears no relation to the sexual experience of a woman. Instead, vaginal corona describes the facts more accurately. [3]

Some scientists assume that the hymen offers female infants and young girls a special protection against germs. Others consider it an evolutionary relict which nowadays no longer serves its purpose. [4] [5]

Culture
The myth that the hymen ruptures during first sexual intercourse is still present today. It probably goes back to the biblical narrative about the Virgin Mary who gave birth to her son in a pure and untouched state. [6]

In many cultures and religions, an intact hymen is highly valued at marriage in the belief that this is a proof of virginity. Thus, a "real" virgin has to bleed at consummation of marriage and bloody sheets prove a decent woman. For this reason, some women undergo hymenorrhaphy, a restoration of their hymen. This 20 minute-long surgery is also called revirgination. Other women get by with a synthetic membrane and fake blood which costs between 200 and 400 Euros. [2] [3] [6] [7]

"It's essential to inform society about the varying shapes of the hymen and the variable bleeding in intercourse."
(Bioethicist Verina Wild, Center of Ethics, University of Zurich) [6]
(translated by Christine Wilhelm)

Further Links:
You can't pop your cherry!, Laci Green, 2013 (You Tube)
The Truth About Hymens And Sex, CollegeHumor, 2015 (You Tube)