We all know that sexual intercourse is responsible for the creation of children. The sperm from the father attempts to reach the egg inside the mother and fertilise it. However, the lifespan of a sperm is really not that simple. There are a great number of stages and things that can happen once sperm leave the body.
The first step in the sperm's lifespan is to actually get it out of the man's body. This is done through ejaculation, which is when the muscles contract and force semen out through the penis. This is usually accompanied by an orgasm, which is a feeling of sexual pleasure. Where the semen goes after ejaculation depends on how long the sperm in it live.
Sperm cannot live very long outside of a body. If semen lands outside the vagina or was expelled during masturbation, then the sperm will not live very long. Perhaps an hour at the most. Generally speaking, if the semen is still wet, there could possibly be sperm still living inside of it.
If sperm are expelled into the vagina, then their lifespan increases fairly dramatically. Sperm can live for up to six hours in the vagina, though vaginal secretions and acids break sperm down fairly quickly. If sperm are going to live longer than these six hours, they need to continue to move towards their goal.
Once sperm travels through the cervix, their lifespan increases yet again. Generally speaking, sperm can continue to survive in the Fallopian tubes for three to five days on average, but it's possible that they'll live up to a week. This means that in theory spearm can be left to fertilise an egg up to seven days before ovulation occurs.
There are a number of factors that can increase or decrese the life of sperm outside of the body. Moisture and termperature, warm and damp are better for them. If the woman is currently taking hormones that increase her secretions, sperm won't live as long due to the acids and thickened cervical mucus. If there is any spermicide involved either in a condom or lubricant, that will decrease the sperm's life even further, possibly killing all of them.