ELI5: Explain Like I'm 5

Strong authentication

Strong authentication is a way to make sure that you are really who you say you are when you're using the internet. It usually involves using two different types of identification (known as 'factors') like a password plus something else like a special code that is sent to your phone. This is to make sure that even if someone manages to get your password, they can't gain access to your account or do anything else with it.