The OData protocol is a standardized HTTP-based protocol to retrieve data. Please check : new window for details regarding the standard, programming examples and more.
When accessing an OData service URL via a web browser, you can interactively see the results of OData queries as JSON documents or XML documents.
Accessing data via an OData service is quite simple. Basically, all you need is to create an HTTP-based request with basic authentication turned on. The user name is the e-mail address and the password is the one created via “Password for Applications”.
The response is always a JSON document. In many programming languages, there is already a good toolset to parse and interpret JSON.
Note: If you have to process the metadata as well, simply follow the URLs stored in @odata.context which you can see in the screenshot below.