The latest version of OData, version 4.0 (plus errata 02), has been publicly standardized by OASIS and is beginning the standardization process with ISO. All new OData implementations should use this version of OData.
To get started learning OData V4, we recommend working through the Beginner Tutorial and Advanced Tutorial first. Next, read Part 1: Protocol for an overview of the OData Protocol. See Part 2: URL Conventions for details on the URL syntax, and Part 3: Common Schema Definition Language for details on the OData Modeling language. Finally, refer to OData JSON Format or OData Atom Format for details on the individual payload formats.