What is the difference between OData and WCF Data Services ?

Q: What is the difference between OData and WCF Data Services?

A: OData is a protocol for querying data, while WCF Data Services is one particular implementation of this protocol. WCF Data Services (formerly known as "ADO.NET Data Services") is a component of the .NET Framework that enables you to create services that use the Open Data Protocol (OData) to expose and consume data over the Web or intranet by using the semantics of representational state transfer (REST).