What is two-factor authentication?
Two-factor authentication adds an extra layer of security to your account by combining what you already know (your login details) with something you physically have access to (your smartphone).
If you enable two-factor authentication, each time you log in you’ll be asked for your username, random characters from your password, and the answer to your security question. You’ll then be asked to use your smartphone to generate a random 6-digit code.
That way, even if someone gets hold of your login details, they still won’t be able to access your account as long as you still have your phone.