Alan has a web application that shows you all funny tweets. In order to see those tweets you must first create an account.
Username/Pass
You pick a username, you enter a password. That combination is attached to Alan WebApp UserID: 12345
Everytime you login with that username and password combination, you get back Alan WevApp UserID 12345.
Google Login
You click the "Login with Google" button.
It redirects you to say "Do you want to associate your google account with Alans Web App?"
You click yes.
Google ID: XYZZY is returned. That id is tied to Alan WebApp UserID 12345.
The next time you go to login, Google returns "This is Google ID: XYZZY". Alan WebApp finds the association XYZZY with Alan WebApp 12345.
Alan has a web application that shows you all funny tweets. In order to see those tweets you must first create an account.
Username/Pass
You pick a username, you enter a password. That combination is attached to Alan WebApp UserID: 12345
Everytime you login with that username and password combination, you get back Alan WevApp UserID 12345.
Google Login
You click the "Login with Google" button.
It redirects you to say "Do you want to associate your google account with Alans Web App?"
You click yes.
Google ID: XYZZY is returned. That id is tied to Alan WebApp UserID 12345.
The next time you go to login, Google returns "This is Google ID: XYZZY". Alan WebApp finds the association XYZZY with Alan WebApp 12345.