The three types of authentication are something you KNOW, something you HAVE, and something you ARE. A multifactor authentication uses 2 or more of these factors. A credit card is something you HAVE while a PIN is something you know.
Multi-factor authentication (MFA) is a method of confirming a user's claimed identity in which a user is granted access only after successfully presenting 2 or more pieces of evidence (or factors) to an authentication mechanism: knowledge (something they and only they know), possession (something they and only they have), and inherence (something they and only they are).
Two-factor authentication (also known as 2FA) is a type (subset) of multi-factor authentication. It is a method of confirming …