Castle doctrine is a rule that says people are allowed to protect their own homes by using force. Imagine you have a toy that you love very much and one day a stranger comes to your house to take it away from you. If your parents or guardians are not there to help, you might have to use force to defend your toy and your home. Similarly, grown-ups are allowed to use force to protect their homes if someone tries to break in or harm them. This is called the castle doctrine because your home is like a castle and you're allowed to protect it. However, it's important to remember that this rule can be different in different countries and states, and it's always best to avoid violence if possible, and call the police for help if your home is in danger.