The term child abduction includes two legal and social categories which differ by their perpetrating contexts: abduction by members of the child's family or abduction by strangers:
Parental child abduction is the unauthorized custody of a child by a family relative (usually one or both parents) without parental agreement and contrary to family law ruling, which may have removed the child from the care, access and contact of the other parent and family side. Occurring around parental separation or divorce, such parental or familial child abduction may include parental alienation, a form of child abuse seeking to disconnect a child from targeted parent and denigrated side of family. This is, by far, the most common form of child abduction.
Abduction or kidnapping by strangers (by people unknown to the child and outside the child's family) is rare. Some of the reasons why a stranger might kidnap an unknown child include:
extortion to elicit a ransom from the parents for the child's return
illegal adoption, a stranger steals a child with the intent to rear the child as their own or to sell to a prospective adoptive parent