Basics of Entity Framework

history of important versions of EntityFramework: 

EntityFramework Version	Introduced Features
EF 3.5	Basic O/RM support with Database First approach.
EF 4.0	POCO Support, Lazy loading, testability improvements, customizable code generation and the Model First approach.
EF 4.1	First to available of NuGet package, Simplified DBContext API over ObjectContext, Code First approach. EF 4.1.1 patch released with bug fixing of 4.1.
EF 4.3	Code First Migrations feature that allows a database created by Code First to be incrementally changed as your Code First model evolves. EF 4.3.1 patch released with bug fixing of EF 4.3.
EF 5.0 - Current release	Announced EF as Open Source. Introduced Enum support, table-valued functions, spatial data types, multiple-diagrams per model, coloring of shapes on the design surface and batch import of stored procedures, EF Power Tools and various performance improvements.
EF 6.0 - Future release	EF 6.0 is currently in pre-release state. It will include Task-based async, Stored Procedures & Functions in Code First and Custom Code First conventions.