Passwords can escape your control
A password can be exposed through a breach, phishing, malware or reuse on another site. A long, unique password reduces some risks, but cannot prevent every way a password might be obtained. Two-factor authentication adds another requirement to sign-in.
A stolen password is less useful on its own
When a service requires a second factor, knowing the password alone generally does not complete a normal sign-in. An attacker also needs to satisfy the additional check. This is the central benefit of 2FA: it adds another barrier when the first one fails.
Protect the accounts that unlock others
Your primary email deserves particular attention because it often receives password-reset links. Cloud storage, financial services, social accounts and administrator accounts may also hold important information or access. Start with accounts whose loss would have the greatest impact on you.
Understand what the extra layer cannot do
2FA is not an absolute guarantee. A fraudulent page can relay passwords and codes in real time. Malware or a stolen signed-in session may bypass a fresh sign-in altogether. Recovery channels and connected applications can also provide other routes into an account.
Make the layers work together
Combine 2FA with unique passwords, device updates, careful sign-in habits and secure recovery settings. Where supported, consider phishing-resistant authentication. Review your provider’s security options rather than assuming every second-factor method offers the same protection.