# Discovery Document
Discovery documents are available for specific versions of most APIs. Each API's Discovery Document describes the surface of the API, how to access the API and how API requests and responses are structured. The information provided by the discovery document includes API-level properties such as an API description, resource schemas, authentication scopes, and methods.
The Discovery document focuses on the RESTful method of invoking an API. The discovery.apis.list method returns the list of all APIs supported by the Google APIs Discovery Service including the urls for retrieving the REST-based discovery documents.