Mutual authentication means two people or groups of people both verify that the other party is who they say they are. It's like when you meet someone in real life - you both try to make sure the other person is who they say they are. For example, when you meet someone at a party, you might ask them questions or look at their ID. This is a form of mutual authentication! Mutual authentication can also help to keep things secure on the internet - like when you log in to an online account. First, you tell the website who you are (by entering your username and password). Then, the website asks you to prove it (by entering a code sent to your phone). Once both of you have verified each other, you can log in safely and securely.