What does FEDERATION mean in SSO world?

[Suggy]

What exactly does Federation mean?

Below image and docs talk about Federated IDP and SSO associated IDP. 

What exactly does it mean in ServiceNow context, especially wrt below image?

Is there any plugin for federation? any configuration for federation? what happens with federation and without federation? 

When should I set  "Source field as federation: xxx " vs "Source field as SSO: xxx"

Docs link: Multi-Provider SSO (SAML) IdP authentication flow

I have implemented sso many times but coming across this federation keyword and configuration details now only hence this question.

[Suggy]

Anyone.?

[PrashantLearnIT]

Hi @Suggy 

Federated identity management (FIM), also known as federated SSO, refers to the establishment of a trusted relationship between separate organizations and third parties, such as application vendors or partners, allowing them to share identities and authenticate users across domains.