The Metrics Query API allows you to execute queries on various metrics and retrieve multiple time-series (data-points) over time from HTTP endpoints. For more information see Metrics - Classic.
Refer to Getting Started for Authentication and Endpoint information.
Sumo Logic has several deployment types, which vary by geographic location and the date an account is created. Select the documentation link below that corresponds to your deployment. If you're not sure, see How to determine your endpoint.