Semen is the milky fluid released when a man has sex. Its purpose is to help sperm survive the journey to the female's egg. Each ejaculation releases about a spooonful of semen. This may seem little but it contains about 500 million sperm! Each sperm can make a woman pregnant. To avoid pregnancy use a family planning method. Semen may also carry infections such as HIV-the best way to prevent infections passing from person to person is to abstain from sex or use condoms every time.
Attribution: Straight Talk Foundation & Marie Stopes