Biologically, a child (plural: children) is generally a human between the stages of birth and puberty. Some vernacular definitions of a child include the fetus, as being an unborn child. The legal definition of "child" generally refers to a minor, otherwise known as a person younger than the age of majority. "Child" may also describe a relationship with a parent or, metaphorically, authority figure, or signify group membership in a clan, tribe, or religion; it can also signify being strongly affected by a specific time, place, or circumstance, as in "a child of nature" or "a child of the Sixties".

The term "child" is sometimes used as a generic term for sons and daughters of any age, with the clarification "adult child" where appropriate. Such people are legally adults, not children, and this article does not apply to them.