Multi-factor authentication (MFA) is an authentication method that requires the user to provide two or more verification factors to gain access to a website or application. The point of MFA is to create a layered defense and make it more difficult for unauthorized people to access the system.

The three main types of authentication factors are:

1. Something you know – This is typically a password or PIN that only the authorized user knows.

2. Something you have – This refers to a physical token or device that only the authorized user has possession of like a security key or code from an authentication app.

3. Something you are – It uses biometrics to verify identity based on unique physical characteristics like fingerprints, retina scans, or facial recognition.

By requiring at least two factors from separate categories, there is a higher level of confidence that the person accessing the account is indeed the authorized user. If the password is compromised in a data breach, for example, the account is still protected by a second factor.

Some common examples of MFA include:

– Users enter username and password (something they know) plus a one-time passcode sent via text message or authentication app (something they have).

– Swiping an ID card (something they have) plus fingerprint scan (something they are) to enter a building.

– Providing an account password along with inserting a registered security key into the USB drive.

The major advantage of multi-factor authentication is the enhanced account security. It protects against phishing schemes, brute force attacks, and many forms of identity theft. If a cybercriminal manages to steal the username and password, they will be unable to access the account without the second authentication factor. That significantly reduces the risk of unauthorized access.

Implementing MFA does introduce potential usability issues. The extra login steps could frustrate some users. Administrators also have to consider workarounds for users who lose access to their second factor. However, with the increasing cyber threat landscape, the security trade-off is usually worthwhile for organizations dealing with sensitive information or financial systems. MFA represents a leading best practice for access management.