Language-Integrated Query (LINQ) as MSDN definition is a groundbreaking innovation in Visual Studio 2008 and the .NET Framework version 3.5 that bridges the gap between the world of objects and the world of data.

 Definitely you have faced some kind of tasks that required from you to deal with various data source such as SQL Database, XML document or Strongly typed of objects, and you have to do some operations on it, such as fetching data, saving data … etc, in that case you need to learn different query language or different syntax for each data source type and writing couple of complex statements, fighting with crazy loops and sets of objects and finding the most efficient object that match your requirements, and so on.

 LINQ makes these things get to be easier to deal with, and provide us a new rich query language that become a part of .NET platform.  You can say SQL statements are become part of the C# and VB.net code, you do not need to use SQLCommand or any other ADO.NET classes to write queries; you can simply use these SQL statement (keywords and familiar operators) within your code.