A gatekeeper parent is a mom or dad who controls access to their child. Think of it like they are the gatekeeper of a castle, and they decide who is allowed to come in and see the prince or princess.
When someone wants to see the child, like a grandparent or a friend, the gatekeeper parent decides if it's okay or not. They might also make rules about how long the visitor can stay or when they can come back.
The gatekeeper parent might do this because they want to protect their child and make sure they are safe. But sometimes, they might go too far and not let anyone see the child, or make it hard for the other parent to spend time with them.
It's important for the gatekeeper parent to find a balance between protecting their child and letting them have healthy relationships with other people.