The ADO.NET Entity Data Model item template is the starting point to the Entity Data Model tools. The ADO.NET Entity Data Model item template is available for Visual Basic and C# project types. It can be added to Console Application, Windows Application, Class Library, ASP.NET Web Service Application, ASP.NET Web Application, or ASP.NET Web Site projects. You can add multiple ADO.NET Entity Data Model items to the same project, with each item containing files that were generated from a different database and/or tables within the same database.

When you add the ADO.NET Entity Data Model item template to your project, Visual Studio:

• Adds references to the System.Data, System.Data.Entity, System.Core, System.Security, and System.Runtime.Serialization assemblies if the project does not already have them.
  
• Starts the Entity Data Model Wizard. The wizard is used to generate an Entity Data Model (EDM) from an existing database. The wizard creates an .edmx file, which contains the model information. You can use the .edmx file in the ADO.NET Entity Data Model Designer to view or modify the model.
  
• Creates a source code file that contains the classes generated from the conceptual model. The source code file is auto-generated, and is updated when the .edmx file changes, and is compiled as part of the project.
  

  Note
  The source code file is not intended for general use. Any manual changes to the file are overwritten when the corresponding .edmx file changes.