Critical thinking is the process of using your mind to think carefully and deeply about a problem or situation. It means you don't just accept what someone says or what you hear, but instead you think about it and decide if it makes sense. When you are thinking critically, you are using your brain to examine evidence and make reasoned and thoughtful decisions. For example, instead of believing that dogs are mean just because your friend said it, you could look into it more closely by reading articles and talking to people who have experience with dogs. That would help you form your own opinion on the matter.