OpenID Connect is a protocol for any site (and other software) to ask an identity provider who the user accessing the site is. Generally the user chooses one pr

OpenID Connect is a protocol for any site (and other software) to ask an identity provider who the user accessing the site is. Generally the user chooses one provider among those supported by the site (e.g. Google, Facebook, etc) and gets redirected to it, so it can authorize the authentication, then gets sent back to the site, and the site can now get info about them (usually some ID, and an email address). This allows the site/user to avoid having to provide and store a password, since the site can just create an account and login the user based on the ID given by the provider. Apple started using that protocol, allowing sites to authenticate users with them, but it broke a few parts of the standard, which meant the site developers couldn't use their normal libraries to connect to Apple's identity provider.