What is Auth custom scopes in Salesforce?

Hi,

A connected app can use the OAuth authorization protocol to access protected resources. As part of the protocol, OAuth default scopes fine-tune the app’s permissions to access protected resources in Salesforce. However, these default scopes are insufficient when an external entity is hosting the protected resource. In this scenario, Salesforce plays the role of OAuth authentication and authorization provider, but it has little knowledge about the resource it’s protecting. To define a connected app’s permissions to access protected resources hosted by an external entity, create an OAuth custom scope. The custom scope tells the external entity which information the connected app is authorized to access.