Hi @daxeshshukla6,
Thanks for reaching out to the Auth0 Community!
I understand that you are asking for clarification on how SSO works when using the Universal Login.
Behind the scenes during SSO login, Auth0 will set an SSO Cookie and redirect the user to your application with an ID Token.
The SSO Cookie is used to check the user’s user session to determine if it’s valid.
Hence, during subsequent logins, the application will check if an SSO cookie exists previously in the browser session. If so, the user continues onto the application without being prompted for their credentials. If the session is invalid, the user will be prompted to submit their credentials again to log in.
Please see here to learn more about how SSO works.
Lastly, you may also find the How do I configure (SSO) Single Sign-On with Auth0? FAQ useful.
Please let me know if you have any questions.
Thank you.