So, you know how mommy and daddy take care of you and make sure you're safe and happy? Well, they have a special responsibility to take care of you because they are your parents. This is called "parental responsibility."
When mommy and daddy aren't together anymore, sometimes they need to decide who gets to take care of you more often. This is called "custody." They might also decide that you get to spend time with both of them, and that's called "access."
Just like when you have a toy, you want to make sure that you get to play with it sometimes and that your friends get to play with it sometimes too. Mommy and daddy want to make sure they both get to spend time with you and take care of you.
Sometimes, a judge might have to help mommy and daddy decide who gets custody and access. But always remember that mommy and daddy love you and want what's best for you, even if they don't always agree on everything.