Adoption is a process whereby a person assumes the parenting

Parenting

Parenting is the process of promoting and supporting the physical, emotional, social, and intellectual development of a child from infancy to adulthood...

 for another and, in so doing, permanently transfers all rights

Rights

Rights are legal, social, or ethical principles of freedom or entitlement; that is, rights are the fundamental normative rules about what is allowed of people or owed to people, according to some legal system, social convention, or ethical theory...

 and responsibilities from the original parent or parents. Unlike guardianship or other systems designed for the care of the young, adoption is intended to effect a permanent change in status and as such requires societal recognition, either through legal or religious sanction.