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What is two-factor authentication (2FA)?

Learn how 2FA protects identities with two-step verification and why businesses use it to protect their apps, resources, and data.
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Two-factor authentication strengthens account security by requiring two forms of identity verification. It helps prevent unauthorized access, reduces the risk of breaches, and supports compliance across systems and users.

Key takeaways

  • Two-factor authentication strengthens sign-in security by requiring two distinct forms of identity verification.
  • Using 2FA helps prevent unauthorized access, even if a password is stolen or compromised.
  • Common 2FA methods include mobile app push notifications with approvals, SMS codes, biometrics, and physical security keys.
  • 2FA reduces the impact of phishing, credential theft, and brute-force attacks.
  • Implementing 2FA supports compliance and protects both personal and organizational data.
  • Built-in Microsoft tools like Authenticator and MFA make secure sign-in simple and scalable.

What is 2FA?

Two-factor authentication is a security method that adds a second layer of identity verification. Instead of relying on just a password, 2FA requires you to confirm your identity using two distinct factors. This reduces the risk of unauthorized access, even if a password is compromised.

How 2FA works

The factors that make up 2FA include:
 
  • Something you know: a password, PIN, or passphrase.
  • Something you have: a physical device like a smartphone, security token, passkey, or smart card.
  • Something you are: biometric identifiers such as a fingerprint, facial recognition, or voice match.
When a system uses exactly two of these categories, it qualifies as two-factor authentication. This makes 2FA a specific subset of multifactor authentication (MFA), which may use two or more factors.

Why 2FA matters

Passwords alone—even when supported by strong password protection policies—are no longer enough to protect against cyberthreats. Phishing, credential stuffing, password sharing, and brute-force attacks can all compromise single-factor authentication. 2FA helps mitigate these risks by requiring a second form of verification, something that’s much harder for attackers to replicate or steal.

By requiring an additional factor, 2FA provides stronger protection for user accounts, sensitive data, and organizational resources. It's one of the simplest and most effective steps to improve your overall security posture.

How does 2FA work in the real world?

The 2FA process adds a real-time verification step to the standard login security workflow. This timely approach makes it much harder for attackers to access your account, even if they have your password.

What a typical 2FA process looks like

Here’s how 2FA usually works during a login:
 
  • You enter your username and password as usual.
  • You're prompted to complete a second verification step using:
    • A push notification with approval or a time-sensitive code from an authentication app like Authenticator.
    • A time-based one-time password (TOTP) sent via SMS or email.
    • A biometric scan, such as a fingerprint or facial recognition.
    • A physical security key inserted into a device or tapped via near-field communication (NFC.)
Why timing matters

Most 2FA TOTPs are short-lived, often expiring in 30 to 60 seconds. This limits the window in which an attacker could use a stolen code. The real-time nature of this process is what makes 2FA more secure than relying on a password alone. It ensures that access is tied to both your credentials and your physical presence or device at the moment of login.

Common types of 2FA methods and how they work

You have several options when choosing a second factor to combine with a password, each with different levels of security and convenience.

Most common 2FA methods
 
  • SMS codes are one-time codes sent to a trusted phone number via text message. This is one of the most widely used methods, though it's less secure than others due to risks like SIM swapping.
  • Push notifications are prompts sent to a mobile app like Authenticator. Users tap “approve” or “deny” to confirm a login attempt.
  • Hardware tokens are physical devices such as key fobs that generate time-based, one-time codes. This is one of the oldest forms of 2FA, now less commonly used.
  • Voice calls, or automated systems that call a user and deliver a verification code by voice, are often used as a fallback or accessibility option.
  • Biometric factors include fingerprint scans, facial recognition, and iris scans. As these technologies become more available, they’re becoming a popular second factor, especially on mobile devices.
The shift toward password-free authentication

While traditional 2FA relies on passwords plus a second factor, password-free sign-in is gaining ground. This approach uses strong authentication methods like biometrics, or passkeys, eliminating the need for passwords entirely. Even without a password, the principles of 2FA still apply: you must present multiple types of evidence to verify your identity.

Key benefits of 2FA for businesses and individuals

Adding 2FA is one of the most effective ways to improve identity security. It helps protect both employee and customer accounts from unauthorized access, reduces the risk of data breaches, and supports regulatory compliance, without adding friction to the login experience. As part of a Zero Trust approach, 2FA ensures that every access request is verified, regardless of location or device.

Why use 2FA?

You can rely on 2FA to:
 
  • Protect sensitive employee and customer data.
  • Prevent account takeovers and unauthorized system access.
  • Strengthen defenses against targeted attacks and stolen credentials.
Core advantages of using 2FA
 
  • Better protection against stolen passwords. Even if a password is compromised, attackers still need a second factor to access an account.
  • Reduced impact of phishing, credential stuffing, and brute-force attacks. These common threats are much less effective when 2FA is in place.
  • Convenience. Many modern 2FA methods, like push notifications and biometrics, don’t require extra devices.
  • Supports regulatory compliance. Two-factor authentication helps meet the security requirements of frameworks like International Organization for Standardization (ISO) 27001, National Institute of Standards and Technology (NIST) guidelines, the General Data Protection Regulation (GDPR), and the Health Insurance Portability and Accountability Act (HIPAA).
  • Minimized risk of data breaches. Reducing unauthorized access lowers the chances of both personal and business data exposure.

How to bring 2FA into your organization

Implementing 2FA is a practical step toward reducing risk for both personal and business accounts. It adds a layer of defense around vulnerable networks, databases, and identity systems, making it harder for attackers to gain access, even with stolen credentials.

Best practices for successful 2FA adoption

To get the most value from 2FA and ensure an excellent user experience:
 
  • Register multiple devices or backup options. Prevent accidental lockouts by allowing users to add secondary devices or generate backup codes.
  • Educate people on safe usage. Help employees recognize phishing attempts, confirm trusted apps and websites, and understand when and how to respond to 2FA prompts.
  • Manage trusted devices wisely. Limit how often users are prompted to authenticate on personal or managed devices without sacrificing security.
  • Provide secure recovery options. Support account recovery with alternate sign-in methods or securely stored backup codes to reduce support overhead.
Setting up and managing 2FA with Authenticator

With support for push notifications, time-based codes, and biometric sign-in options, the Authenticator app simplifies the 2FA experience across both personal and business devices. Users can manage their accounts, add new sign-in methods, and monitor activity, all from one place. Organizations can use the Authenticator app with Microsoft Entra ID to support scalable deployment and policy management. For organizations using identity federation or single sign-on, Microsoft Entra ID supports integration with modern protocols like OpenID Connect (OIDC) to enforce 2FA consistently across cloud and on-premises environments. Get a step-by-step MFA deployment guide.

What’s the difference between 2FA and MFA?

Two-factor authentication and MFA are related but not interchangeable. Both involve verifying identity with more than just a password, but there’s a key distinction in how many factors are required:
 
  • 2FA uses exactly two distinct factors to verify identity. For example: entering a password (something you know), then confirming a code sent to your phone (something you have).
  • MFA is a broader category that includes two or more factors. This could mean combining a password, a mobile app prompt, and a fingerprint scan.
So, all 2FA is MFA, but not all MFA is limited to two factors.

Why organizations choose MFA

Organizations with higher security needs often adopt MFA to:
 
  • Meet stricter compliance requirements.
  • Protect sensitive systems or high-privilege accounts.
  • Reduce the likelihood of successful phishing or impersonation attempts.
Adding a third factor, such as biometrics or a physical security key, adds complexity for attackers without significantly slowing down legitimate users.

Microsoft recommends that organizations set up MFA for all users and ensure backup methods are in place. Relying on just two factors, especially when one factor depends on a single channel like SMS, can introduce risk. Multifactor authentication with redundant options helps ensure continued access if one method becomes unavailable, such as during a phone network outage.

How strong authentication is built into Microsoft security solutions

Strong authentication is built into Microsoft tools you already use to sign in, protect sensitive data, and meet compliance goals. Whether you're managing personal accounts or securing an enterprise environment, these features support safer access across devices and services.

Secure sign-in for personal and professional accounts

Protect identities with push notifications, time-based codes, and biometric options like facial recognition or fingerprints with the Authenticator app. Approve sign-ins with a tap, no password required. The app also supports non-Microsoft accounts to keep everything in one place.

Flexible enforcement across organizations

In business settings, MFA through Microsoft Entra supports a wide range of methods, including:
 
  • One-time passcodes.
  • Push notification with approvals.
  • Text messages and voice calls.
  • Certificate-based authentication.
  • Biometric sign-in with Windows Hello.
  • Passkeys.
Security teams can apply policies that require 2FA in specific scenarios, such as unfamiliar sign-ins, high-risk applications, or unmanaged devices. These policies adapt to user context without adding unnecessary friction.

Support for recovery and continuity

To keep everyone connected and secure, Microsoft services allow multiple sign-in methods and recovery options. If your device is lost or reset, you can rely on backup codes or alternate methods to regain access without compromising security.

Integrated authentication features like these help reduce the risk of account compromise, simplify identity management, and support evolving access control needs.
Resources

Learn more about 2FA

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Product feature

Strengthen sign-in security with Microsoft Entra MFA

Add two-factor or multifactor authentication to protect users and data.
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Solution

Secure apps and data across your organization

Use an identity and network access solution to manage access, enforce policies, and reduce risk.
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Frequently asked questions

  • Two-factor authentication (2FA) is a login process that requires two different types of identity verification to access an account. Typically, this involves something you know (like a password) and something you have (such as a mobile device or security key). By requiring both, 2FA adds a layer of protection against unauthorized access.
  • Two-factor authentication (2FA) protection works by requiring users to verify their identity using two separate methods before gaining access. This reduces the risk of unauthorized access, even if a password is compromised. It protects against common threats like credential theft, phishing, and brute-force attacks.
  • An example of two-factor authentication (2FA) is signing into an account with a password and then confirming a code sent to your phone. This combines something you know (the password) with something you have (the phone). Other examples include using a fingerprint or approving a login via an authentication app like Authenticator.
  • Two-factor authentication (2FA) helps prevent unauthorized access to accounts by adding a second layer of identity verification. It reduces the risk of data breaches caused by compromised passwords and supports compliance with security standards. Many organizations use 2FA to protect sensitive systems and user identities.
  • Two-factor authentication (2FA) is a key component of the Zero Trust security model, which assumes no user or device should be trusted by default. In a Zero Trust architecture, 2FA helps verify identity before granting access to applications or data, supporting the principle of “verify explicitly.”
  • Two-factor authentication (2FA) can reduce the success of phishing attacks by requiring a second verification step beyond a stolen password. To enhance protection further, consider adopting phishing-resistant multifactor authentication (MFA) methods such as hardware security keys or passkeys, which defend against adversary-in-the-middle attacks.
  • Two-factor authentication (2FA) is important because it adds an extra layer of security to user accounts, helping prevent unauthorized access. It protects against threats like password theft, phishing, and automated attacks. 2FA is widely recommended as a baseline security measure for individuals and organizations alike.

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