Setting up Multifactor Authentication (MFA) for Microsoft 365

What is MFA and why do I need it? By setting up MFA, you add an extra layer of security to your Microsoft 365 account sign-in. For example, you first specify your username and password and, when prompted, you also type a dynamically generated verification code provided by an authenticator app or sent to your phone. If somebody else tries to sign in as you, they'll enter your username and password, then when they get prompted for that second factor they're stuck! Unless they have YOUR smartphone, [...]