How old must I be to adopt a child?

if you are legally an adult in your country you are fine to adopt, but not just any adult can adopt, the adoption agencie will check if you are finnancialy stable, what sort of house you live in, if you are in a relationship, if you have any other kids, if you have pets etc. then you are put on a waiting list with all your details then you are either picked buy somebody that is giving up there child as a patential person to adopt or in other cases the agencie will contact you them selves if they feel you are suitable