What Is A Child? What Is The Meaning Of Childhood? What Is Child Labour?

The question you ask is very difficult to answer.  Many people have different views about the answer to this question.  If you just want to know for personal curiosity, then good for you!  You have an inquisitive mind!  If you need to know for some other reason, then I'm  not exactly the right person to help you.  A presentation or report about such would need information from an official source.  But if its curiosity, I can help.  A child is someone who is still in the process of growing into an adult.  A child is someone who is still learning about the world around them.  Which is why you hear the expression "find the the child in you".  Also, think about the fact that (if you're Christian) we are all god's children.  So, we are all, technically still learning about the world around this until the day we die.

In legal terms as concerns child labor law, a child is a minor under the age of legal eligibility to work for compensation in a public business, except for some very limited types of labor (such as delivering newspapers, for example).  In the US, this varies by state, and is generally around the age of 13 or 14.

For the US, you may learn more about the legal definition of a child/minor as relates to labor law by going to this link:
Child Labor Laws in the US

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US Dept of Labor on Child Labor Law