What is Multi-Factor Authentication in AWS

A way to protect your AWS Accounts via Multi-Factor Authentication by way of Password that you know as well as a security device that you own

The number one benefit of MFA is that if your account is hacked or stolen then the account cannot be compromised

Multi-Factor Authentication Devices in AWS

Virtual MFA Devices such as Google Authenticator and Authy
Universal Second Factor (U2F) Security Key which is a physical device (Yubi as an example)
Hardware Key Fob such as Gemalto
AWS GovCloud for US based authentication