Child abandonment is when a grown-up person who should take care of a child leaves the child without any plan to make sure they are safe and looked after. This means that the child is left all alone or with someone else who may not be able to take proper care of them.
It's like when you bring your toy to your friend's house to play and then you leave it behind and forget about it. But a child is not a toy and needs someone to take care of them all the time.
This is a very bad thing to do to a child because they can get very scared and they may not have anyone to take care of them. It's important for grown-ups to be responsible and take good care of kids because they need it to grow up healthy and happy.
If you ever feel like you've been left alone and no one is taking care of you, tell someone you trust. You can talk to your parents, a teacher or a police officer. They will help you and make sure that you are safe.