This question already has an answer here:

Various sites use a multi-page login. On the first page the user is chosen (i.e. email address), and on the second page, a password is given.

Many banks use it, Google has this also.

I first thought this could prevent phishing, but actually it would not. What makes this more secure, why are banks using it? It feels like a cargo cult to me: "they use it, we better do that too."

Google also released info about it (this is all I found):

This new Google account sign-in flow will provide the following advantages:

  • Preparation for future authentication solutions that complement passwords
  • Reduced confusion among people who have multiple Google accounts
  • A better experience for SAML SSO users, such as university students or corporate users that sign in with a different identity provider than Google

But that does not seem compelling to me.

marked as duplicate by Tom K., Steffen Ullrich, Community Aug 28 '18 at 11:28

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.