Your Apple ID is the account you use to sign in to all Apple services such as iCloud, and to be able to purchase and download free apps.
Each person using an iPhone, iPad or Mac should have their own Apple ID, rather than share an Apple ID with another family member.
Children under 13 can't make an Apple ID, however you as their parent can make one for them under Family Sharing. This has the bonus of being able to share purchases of apps – so you don't have to buy an app again for other family members.
We encourage families to create an Apple ID under Family Sharing for their child to use with their iPad.
Family Sharing makes it easy for up to six family members to share music, films, TV shows, apps, books, an iCloud storage plan, subscriptions and more — all without having to share an Apple ID.
You can set up an Apple ID for kids, set permissions remotely with Screen Time and approve spending, and approve app downloads from a parent's device with Ask to Buy.
When children are older, you can remove them from Family Sharing, and their account continues – they just can't share your purchases anymore.
Learn how to setup Family Sharing and an Apple ID for your child here: https://support.apple.com/en-au/HT201088