How does sex actually work?

 Sex can be one of three things. Typically, when someone asks how sex works, they are talking about intercourse. Sexual intercourse is best described as the erect penis being placed inside a woman’s vagina.

 There are two other kinds of sex that people sometimes engage in. One is called oral sex. Oral sex is when a person puts his or her mouth on their partner’s genitals (mouth to penis or mouth to vagina). Anal sex is when the penis is placed inside the anus.

All three kinds of sex can pass STDs (sexually transmitted diseases) from one person to the other, although only intercourse also includes the risk of pregnancy.