Passwords remain the default method of user authentication, but the question is for how long? It is becoming more or less an established fact that passwords are insufficient to prevent software threats.
So every time the user enters the password, the app hashes or encrypts the given combination of symbols and compares it to the initially provided password.
The most common approaches are: Email and SMS authentication Authenticator applications Authentication devices and fobs Different forms of https://thenewstack.io/biometrics-brings-us-one-step-closer-to-eliminating-passwords-for-good/
However, with passwordless, these prerequisites should be in place, be it a mobile phone with an authentication app, authentication device or keyfob.