When an endpoint returns a resource representation or list of resource representations, its response may support the expansion of a subresource.
Not all endpoints that return resource representations support expansion. For details about a specific endpoint, refer to its documentation.
To expand a response to include a subresource, use the $expand query parameter to provide the name of the subresource. For example, if an endpoint indicates that a returned resource representation can be expanded to include foo, provide the query parameter $expand=foo.