This probably sounds like a weird title but the actual mechanics of sex are a mystery to some. There are many reasons why people, especially younger people, don’t actually know how sex "works"--what goes where? Who does what? And what does it all mean?
People may not be educated at home, or school. They have parents who would rather skip the whole subject out of embarrassment or have a religious or cultural belief that it’s something not to be spoken of. Others have parents who don’t care enough or don’t make the time. They may miss school or lack the opportunities for sex education there. The results? Pregnancy, disease and misinformation. It can also lead to a fear of sex and sexuality, as well as believing what their peers tell them about sex, which can be dangerous.
So what is sexual intercourse, exactly? It stems from a biological urge that nearly all humans have at one time or another. Human are pre-programmed genetically to have sex so that we can propagate our species, just like any other. Sex also relieves stress and is generally a very healthy activity for people to engage in.
Sex between a man and woman often goes like this: both usually kiss, touch and become sexually excited ("turned on") as the man’s penis becomes hard and a woman’s vaginal area becomes moist. This happens to make it easier and more pleasurable for a man to insert his penis into a woman’s vagina. This feeling is usually a very good one for both and is also emotionally satisfying. The man ejaculates, which causes the release of several million sperm. These sperm start heading up to the woman’s fallopian tubes, in search of an egg.
Women are born with all their eggs (that need fertilization) and as boys mature, they develop sperm (needed to fertilize). A woman has an average 28-day monthly cycle that produces one egg every month, in and around the middle of the cycle, usually day 14, give or take a few days. When this egg is produced, it moves down into her fallopian tubes and waits for sperm. If the woman has sex around this time, she has a chance of getting pregnant. In fact, a woman can get pregnant at almost any time in her cycle, especially a woman with an irregular cycle. There is no real "safe" time to have sex in order to avoid pregnancy.
When a man releases millions of sperm upon ejaculation, they swim up to the fallopian tubes in order to get to the egg. Only one sperm out of these millions will fertilize this egg and this activity starts the process of pregnancy. Within about 10-14 days, a woman is able to take a pregnancy test to see if it’s positive or negative.