With younger children, it makes sense for you to set the rules and explain them. As kids get older and explore more of the online world, you can discuss new rules together.
The most important rule is that if anything ever happens online that makes your children scared, worried or uncomfortable, they should come to you or to another adult they trust. Make sure they know that you’re on their side: a lot of kids are reluctant to tell their parents when things go wrong because they’re afraid of losing their Internet access or their digital devices.