What is two-factor authentication — and how to turn it on

With two-factor authentication, signing in takes credentials from two of three categories: something you know (a password or PIN), something you have (your phone or a security key) and something you are (a fingerprint or your face). You'll also see it called two-step verification or multi-factor authentication (MFA). The point is simple: a password stolen in a data breach or typed into a phishing page isn't enough on its own.

The methods, from strongest to weakest

• Security keys — small physical keys you plug in or tap. The US FTC calls them the strongest method of two-factor authentication, and Apple recommends them for extra protection against targeted attacks such as phishing.
• Passkeys — a newer way to sign in that replaces the password with a key stored on your device. Apple describes passkeys as resistant to phishing, and Google says passkeys and security keys protect your account from phishing attacks. Strictly, a passkey isn't a second factor: Google skips the second step when you sign in with one.
• Authenticator apps — an app on your phone generates the sign-in codes. Safer than text messages, the US FTC says, because the code can't be intercepted with a SIM swap.
• Codes by text message or email — the most common and the easiest to set up. Google warns that codes sent by text or call can be vulnerable to phone-number-based hacks. Still far better than a password alone.

Where to turn it on first

The US FTC suggests starting with your most sensitive accounts: your bank, credit cards, email and social media. Put email at the top. It's where password-reset links go, so whoever controls your inbox can take over most of your other accounts.

How to turn it on for Apple, Google and Microsoft

• Apple Account: on iPhone, go to Settings > [your name] > Sign-In & Security and turn on two-factor authentication. Apple sends six-digit codes to your trusted devices or phone number. Accounts created with two-factor authentication can't turn it off; if you switched it on yourself, you have two weeks to change your mind.
• Google Account: go to myaccount.google.com, open Security & sign-in, choose 2-Step Verification under How you sign in to Google, and turn it on.
• Microsoft account: go to account.microsoft.com/security, choose Manage how I sign in, and turn on Two-step verification. Microsoft strongly recommends keeping three pieces of security info on the account in case you lose access to one.

Don't lock yourself out

• Save backup codes where the account offers them. Google gives you sets of 10 eight-digit backup codes, each usable once, under Security & sign-in > 2-Step Verification > Backup codes. Keep them somewhere safe and offline.
• Add more than one method — a second phone number, an authenticator app or a security key — so losing your phone isn't the end of the account.
• Update the phone number on your accounts before you change numbers.
• Never read a code out to anyone. A real company won't call or text asking for a code you just received.

Does 2FA replace a password manager?

No — they work together. A password manager gives every account a unique password, so one leak doesn't unlock the rest; two-factor authentication stops a stolen password from being enough on its own. Several security suites include a password manager: Norton on every plan, TotalAV in its Total Security plan, and Avira in its free suite and in Prime.

Turn on two-factor authentication for your email today. It's the account that can reset all the others.