Linq: Deferred Execution

Linq queries are build as you call linq methods but they are not executed until you use the collection.

The power of Linq

Linq is a powerful feature introduced on .NET 3.5 that allows you to easily query your objects to manipulate data.

Entity Framework uses Linq queries to generate database queries and retrieve the data for you. So you don’t have to worry about writing SQL anymore.

Linq also provides methods to work with XML among other things.

From MSDN:

Language-Integrated Query (LINQ) is a set of features introduced in Visual Studio 2008 that extends powerful query capabilities to the language syntax of C# and Visual Basic. LINQ introduces standard, easily-learned patterns for querying and updating data, and the technology can be extended to support potentially any kind of data store. Visual Studio includes LINQ provider assemblies that enable the use of LINQ with .NET Framework collections, SQL Server databases, ADO.NET Datasets, and XML documents.