Most babies are made when a man and woman have sex. Sex is a special, grown up way of being close to someone. When people have sex or make love, it feels good to their bodies.
When a man and woman have sex, their bodies usually get very close together and his penis goes into her vagina. Next some tiny sperm come out of the man's penis. Sperm carry half the traits a baby will inherit from its parents. The sperm are looking for a tiny egg that is in the woman's body. The woman's egg carries the other half of the traits the baby will inherit.
When a sperm finds the egg, they join together. This is the very beginning of a baby. The baby grows in a special place in a woman's body called the uterus, right near her tummy. It takes about 9 months for the baby to be ready to be born. When it's time, the mom's body pushes the baby out of her vagina, and the baby is born!
Sex and this kind of touching is not for kids because kids' bodies aren't grown up and kids aren't ready to take care of a baby. Tell a trusted grown-up right away if anyone ever touches you in this way.
Sometimes when a baby is born, the mom doesn't push the baby out of her vagina. Instead, the doctor does an operation to help the baby be born. This is called a Cesarian Section.