What is multi factor authentication?
Multi factor authentication (MFA) is a security method that requires users to provide two or more pieces of evidence – or “factors” – to verify their identity before gaining access to a system, application, or account.
At its core, MFA is about adding security layers. Rather than relying solely on a password (which, let’s face it, can be guessed, stolen, or reused across multiple accounts), MFA introduces other elements that are much harder for attackers to compromise. This dramatically reduces the chances of unauthorized access, even if a password has been breached.
The three types of authentication factors
MFA works by requiring a combination of different types of credentials. These are typically broken down into three categories:
- Something you know – like a password, PIN, or security question
Something you have – such as a smartphone, hardware token, or security key
Something you are – biometric data like a fingerprint, face scan, or voice recognition
As opposed to single-factor authentication, true “multi factor” authentication must combine at least two different types from the above list. So using two passwords wouldn’t count, but using a password and a fingerprint would.
History of MFA
The concept behind MFA isn’t new. Physical tokens and smart cards have been used for decades in high-security environments, like corporate networks or government systems. On their MFA hub, the United States Cybersecurity and Infrastructure Security Agency (CISA) has even created a simple graphic breaking down the different types of MFA and the technology’s hierarchy of security.
MFA only started showing up in daily life more recently as more of our personal and financial information moved online. It has became clear that passwords alone aren’t cutting it; organizations and industries the world over need a way to ensure the person logging in is actually who they claim to be.
MFA in action
Today, MFA is everywhere – from your email account to your online banking to the admin portal at work. You’ve probably seen it in the form of:
- A code texted to your phone after you log in
- An app notification asking you to confirm a login attempt
- A fingerprint scan required to unlock your device
- A one-time password (OTP) generated by an authenticator app
How multi factor authentication works
At a high level, multi factor authentication is a process that kicks in when you try to log into an account or access a system. Instead of just asking for a username and password, it challenges you to go through identity and access management (IAM) protocols.
- Step 1: You enter your username and password. This is the first factor – something you know. If this information is correct, the system proceeds to the next step.
- Step 2: The system prompts for a second factor. This could be a temporary code, a push notification to your phone, or a biometric scan, depending on what’s set up.
- Step 3: You provide the second factor. Maybe you enter the code from your authentication app, approve a login on your phone, or scan your fingerprint – this is the second piece of evidence, like something you have or something you are.
- Step 4: The system verifies the second factor. If the second factor checks out, access is granted. If not, the login attempt is blocked, even if the password was correct.
- Optional Step 5: You may get a “trusted device” option. Many systems let you mark a device as trusted so you don’t have to repeat MFA every time you log in from it. This helps balance security with convenience.
Benefits of using MFA
Multi factor authentication might feel like a small extra step during login, but that small step packs a serious security punch. By requiring more than just a password, MFA makes it significantly harder for threat actors to compromise accounts – even if some credentials have been exposed. Let’s dive into some of the key benefits of using MFA.
Stronger protection against stolen passwords
Passwords are often the weakest link in security. They can be guessed, reused across accounts, or exposed in data breaches. MFA adds a second (or even third) requirement, making it far less likely that someone can get in with just a stolen password.
Defense against phishing attacks
Even if you accidentally give your password to a phishing site, an attacker still can’t access your account without your second factor. That extra layer often stops an attack in its tracks.
Reduced impact of data breaches
When a company’s database is breached and user passwords are leaked, accounts protected with MFA are far less likely to be compromised – because the attackers still don’t have access to the second factor.
Better control over remote access
MFA is especially useful for employees accessing systems from outside the office. It ensures that even if someone gets hold of login credentials, they still can’t get in without additional proof.
Increased trust and compliance
Many industry regulations and standards (like PCI-DSS, HIPAA, and NIST guidelines) now recommend or require MFA. Using it shows a commitment to protecting user data and helps meet compliance goals.
Common MFA methods and examples
Not all MFA methods are created equal – some are more secure than others, and different options come with their own trade-offs in terms of convenience, cost, and usability.
- SMS or email codes: After entering your password, you receive a temporary code via text message or email that you have to enter to complete the login.
- Authenticator apps: These apps generate time-based one-time passwords (TOTPs) that refresh every 30 seconds. They're more secure than SMS and work even when your phone doesn’t have service. Examples: Google Authenticator, Microsoft Authenticator, Authy
- Push notifications: Instead of typing a code, you get a notification on your phone asking you to approve or deny the login attempt. This is both user-friendly and secure, especially when combined with location or device context.
- Hardware tokens: These are physical devices that either generate one-time codes or connect directly to your computer via USB or NFC. Hardware tokens are highly secure and resistant to phishing but can be lost or forgotten. Examples: YubiKey, RSA SecurID
- Biometric authentication: Biometric factors are increasingly common on mobile devices and laptops. They’re convenient and difficult to spoof, though privacy and accuracy concerns still exist. Examples: fingerprint, face scan, voice recognition
MFA vs. 2FA: What's the difference?
You’ll often hear the terms multi factor authentication (MFA) and two-factor authentication (2FA) used interchangeably – and while they’re closely related, they’re not exactly the same thing. Understanding the difference can help clarify what kind of protection you're actually getting.
2FA is a specific type of MFA
Two-factor authentication is exactly what it sounds like: it requires two different authentication factors – like a password plus a text message code, or a PIN plus a fingerprint.
MFA covers a broader range
MFA is a broader term that simply means using two or more different types of authentication factors. That could be two, three, or more. So, all 2FA is MFA, but not all MFA is limited to just two factors.
More factors can mean more security
While 2FA is usually enough for most everyday accounts, higher-risk environments (like enterprise systems or critical infrastructure) may call for three or more factors. Adding more layers increases security, but also adds complexity.
Quick example: Let's say you log into your bank account with a password and then approve a push notification on your phone. That’s 2FA. If your bank also requires a fingerprint scan on top of that? Now you’ve crossed into full MFA territory – with three distinct factors.
MFA challenges and considerations
Multi factor authentication is one of the best defenses against unauthorized access – but that doesn’t mean it’s without its challenges. Like any security measure, MFA has to strike a balance between protection and usability. Here are some of the common considerations that come into play when implementing or using MFA.
- User experience and convenience: Adding extra steps to the login process can sometimes frustrate users – especially if the second factor is slow, unavailable, or difficult to use. For organizations, this means choosing MFA methods that are secure and user-friendly to avoid pushback or workarounds.
- Implementation complexity: Rolling out MFA across an organization or platform isn’t always straightforward. It involves configuring systems, training users, and possibly integrating third-party tools. The complexity increases when supporting different devices, user roles, or legacy applications that don’t natively support MFA.
Account recovery and backup options: What happens if someone loses their phone or can’t access their second factor? There need to be secure, well-documented recovery processes in place, otherwise users could get locked out of their own accounts. Poorly designed recovery flows can also become a weak point attackers try to exploit.
Accessibility concerns: Not every MFA method is equally accessible to all users. For example, users with disabilities may have trouble using biometrics or hardware tokens. Inclusive design and offering alternative methods can help ensure that MFA doesn't unintentionally exclude anyone.
Cost and resource demands: Some MFA solutions – like biometric systems or hardware tokens – can be expensive to deploy and manage at scale. Smaller organizations or individual users might need to weigh the cost against the risk.
MFA fatigue and “prompt bombing”: Attackers have learned to exploit user behavior by triggering repeated MFA prompts (like push notifications) in hopes that users will eventually approve them out of habit or annoyance. This tactic, sometimes called “MFA fatigue,” highlights the importance of user education, security awareness training, and thoughtful design.
Maintaining trust over time: MFA isn’t a “set it and forget it” solution. Devices change, apps get updated, threats evolve. Ongoing maintenance and monitoring are needed to ensure MFA methods remain effective and that security policies are up to date.