A stepfamily is a family where one parent has children that are not related to the other parent. Either one or both parents may have children from a previous relationship. Children from a stepfamily may live with one biological parent and visit their other biological parent, or they may live with each biological parent for a period of time.

A stepfather is the husband of your mother and not your natural father. A stepmother is your father’s wife and not your natural mother.

About half of all marriages end in divorce, and 75% of those who get divorced decide to remarry. This leads to the creation of millions of stepfamilies each year.

The traditional and strictest definition of a "stepfamily" is a married couple where one or both members of the couple have pre-existing children who live with them. More recently, the definition is often expanded to include all cohabiting couples, whether married or not. Some people also apply the term to non-custodial relationships, where "stepparent" can refer to the partner of a parent with whom the child does not live. The term is not generally used (but can be in individual cases) to refer to the relationship with an adult child who never lived in the home with the parent's new partner.