Traditionally we used to use a username and password to authenticate we are who we say we are and this is known as single factor authentication.
Factors are essentially a piece of evidence that proves your identity to the given system.
A username is not considered a factor because its typically not a confidential piece of information that only you have access to.
What are the different types of factors used in Authentication?
🧠 Knowledge
Knowledge factors are something that you know such as a password or a pin code
💳 Possession
Possession factors are something that you have such as a MFA app/device or a bank card.
👁️ Inherent
Inherent factors are things that are unique about you such as fingerprints, face, iris and voice. Fun-fact: You can even be identified in the way you type.
🗺️ Location
Location factors can either be the physical location in the world or even the network you are connected to.
The more factors used increases the level of security by making it more difficult to fake.
But the more factors used decreases the convivence by making it more difficult to login.