Object Reference for the Salesforce Platform
jCustom Objects
This section provides details on custom objects, entities that support custom
objects, and their standard fields.
When you create or enable features for a custom object, Salesforce creates entities to support your custom object. For example, when you enable sharing rules for a custom object, Salesforce creates a MyObjectName__Share object.
To verify the complete list of fields for an object or entity, you can use a describe call from the API, or inspect with an appropriate tool, for example, inspecting the WSDL or using a schema viewer.