This visa is for migration to Australia as the dependent natural child, adopted child, stepchild (certain circumstances) or orphan relative of an Australian citizen, Australian permanent resident or eligible New Zealand citizen.
If your child is overseas and was adopted after the sponsor became a permanent resident, you should apply for them under the Adopted Child category.
There are various categories of Child visa:
Child (Permanent) visa (subclass 802 for onshore; 101 for offshore): the child must be under 25 years of age and intend to remain in Australia with their parent;
Dependent Child visa (subclass 445): a temporary visa for a child or stepchild of a parent who holds a temporary partner visa (which does not include the child) and has not yet been granted a permanent Partner visa;
Orphan Relative visa (subclass 837 for onshore; 117 for offshore): the child must be under 18 years of age and its biological parents are unable to care for them;
Adoption visa (subclass 102): this visa is for children outside Australia, who are under 18 years of age, and in the process of being, or who have been, adopted by an Australian citizen or permanent resident.