After setting up ADFS I frequently forget the URLs used by ADFS. It’s funny that they don’t really show you these after an install. But here they are and what they are used for.
This is the IDP initiatedsign on page. This is where you can access your relying party trusts. This is used when the relying part does not support SP. (You need to use your ADFS server website to login to their services)
This is your ADFs federated metadata. This data can be published to the internet so that your relying party trusts can read what properties you send over in claims and what you accept. It also publishes your public certificate data so when your ADFS server auto renews certificates other servers can read this data automatically and update their end too. This avoids issues with the cert renewal process (if they support it).
This URL can be used by internal users via the IDP page to log directly into another relying party trust. This way the don’t have to actually use the IDP page manually. You just enter the partner URL found in the ADFS console for your relying party trust.