Entity Framework

Entity Framework (EF) is an open sourceobject-relational mapping (ORM) framework for ADO.NET. It was a part of .NET Framework, but since Entity framework version 6 it is separated from .NET framework.

The Entity Framework is a set of technologies in ADO.NET that support the development of data-oriented software applications. Architects and developers of data-oriented applications have typically struggled with the need to achieve two very different objectives. They must model the entities, relationships, and logic of the business problems they are solving, and they must also work with the data engines used to store and retrieve the data. The data may span multiple storage systems, each with its own protocols; even applications that work with a single storage system must balance the requirements of the storage system against the requirements of writing efficient and maintainable application code.

The Entity Framework enables developers to work with data in the form of domain-specific objects and properties, such as customers and customer addresses, without having to concern themselves with the underlying database tables and columns where this data is stored. With the Entity Framework, developers can work at a higher level of abstraction when they deal with data, and can create and maintain data-oriented applications with less code than in traditional applications. Because the Entity Framework is a component of the .NET Framework, Entity Framework applications can run on any computer on which the .NET Framework (starting with version 3.5 SP1) is installed.

The first version of Entity Framework (EFv1) was included with .NET Framework 3.5 Service Pack 1 and Visual Studio 2008 Service Pack 1, released on 11 August 2008. This version was widely criticized, even attracting a 'vote of no confidence' signed by approximately one thousand developers.

The second version of Entity Framework, named Entity Framework 4.0 (EFv4), was released as part of .NET 4.0 on 12 April 2010 and addressed many of the criticisms made of version 1.

A third version of Entity Framework, version 4.1, was released on April 12, 2011, with Code First support.

A refresh of version 4.1, named Entity Framework 4.1 Update 1, was released on July 25, 2011. It includes bug fixes and new supported types.

The version 4.3.1 was released on February 29, 2012. There were a few updates, like support for migration.

Version 5.0.0 was released on August 11, 2012 and is targeted at .NET framework 4.5. Also, this version is available for .Net framework 4, but without any runtime advantages over version 4.