Microsoft’s Entity Framework 1 was initially replease as part of Visual Studio 2008 SP1. It was created as an object-relational mapping (OR/M) tool that is used to create an abstraction layer on top of ADO.NET namespaces with two methodologies: Database First approach and Model First.
Now there’s a new approach available: Entity Framework Code First. It enables developers to use nothing but code–ditching the previous requirement of using designer or .edmx files to create the domain model.
The idea behind Code First is to provide a simple API for an EDM runtime configuration, which provides a second alternative. This allows developers to write code and utilize conventions for configurations and modeling, rather than XML files.