A hymen is a thin, flexible membrane of tissue that partially covers the opening of the vagina. It is made of connective tissue, muscle fibers, blood vessels, and nerve endings. The shape of the hymen can vary, with common types including annular (ring-shaped) and crescentic (crescent-shaped), and it often thins or stretches over time due to various activities. The hymen can stretch and thin over time due to activities like exercise, horseback riding, or inserting a tampon, not just sexual intercourse. When someone with a hymen does have sex for the first time there can be a little blood, a few spots of blood or absolutely no blood. Some people feel no discomfort when the hymen is broken, where others feel a sharp stabbing pain or a burning sensation, which causes the vagina to contract then gradually relax, and the person will find the pain slowly fading provided their partner pauses to let them adjust to the penetration. If the penetrating partner does not pause, the discomfort or pain is prolonged until the vaginal muscles relax enough for penetration to feel less invasive.