Two-step verification helps protect you by making it more difficult for someone else to sign in to your Microsoft account. It uses two different forms of identity: your password, and a contact method. Even if someone else finds your password, they'll be stopped if they don't have access to your other devices or accounts. (This is also why it's important to use different passwords for all your accounts.)
You set up two-step verification with an email address, phone number, or authenticator app. When you sign in on a new device or from a new location, we'll send you a security code to enter on the sign-in page.
If you turn on two-step verification, you’ll get a security code to your email, phone, or authenticator app every time you sign in on a device that isn't trusted. When it’s turned off, you will only have to verify your identity with security codes periodically, when there might be a risk to your account security.
Go to the Security settings page, and sign in with your Microsoft account.
Under Two-step verification, choose Set up two-step verification to turn it on, or choose Turn off two-step verification to turn it off.
Follow the instructions.
Some apps (like the mail apps on some phones) or devices (like the Xbox 360) can't use regular security codes. If you see an “incorrect password” error on an app or device after you turn on two-step verification, but you’re sure your password was correct, that means you'll need an app password for that app or device.
Under App passwords, click Create a new app password. The new, unique app password will appear on your screen.
In the app or device you’re trying to use, enter that new app password instead of your regular password.
App passwords are only necessary if you use two-step verification. If you don't see the App passwords section on the Security settings page, you may not have two-step verification turned on.
App passwords and two-step verification
Trusted devices: FAQ
Security info & security codes
Email Microsoft support
Chat with Microsoft support