If your product requires users to share sensitive information — like their credit card details — it most likely already has two-factor authentication. It's a security process in which users need to verify themselves twice, most commonly with:

• A login and password
• A security token (e.g., one-time passwords)
• A biometric factor (a fingerprint or facial scan)^[1]

Consider adding two-factor verification when changing important information, such as an email address, billing info, etc. This will ensure that users can avoid any unauthorized or accidental changes.