|The age at which children are considered responsible for their society-bound actions (e. g. marriage, voting, etc.) has changes changed over time. Kids and teens are two different age groups without a well defined boundary. This is because different cultures define the age boundaries differently (if they define them precisely at all) or because the norms and tradition may also vary over time.
Age definition are also reflected in the way kids and teens are treated in courts of law which often has more specific definitions of the age boundaries.
In our modern society kids are generally thought of as being under the age of 12 and teens are 13 and above. In today's society kids and teens represent a specific demographic niche and this is also recognized by marketer and kids and teens are now a specific market niche.