We've written a new guide on Federated Identity (FedCM).
The articles helps you to understand what's happening under the surface when a website works with an identity provider (IdP) to add federated sign-in for their users.
We cover the main flows as defined in the OpenID Connect (OIDC) protocol and its security features.
We also present how the FedCM API helps with moving away from third party cookies, and we list some strengths and weaknesses of Federated Identity.
https://developer.mozilla.org/en-US/docs/Web/Security/Authentication/Federated_identity
