Language Integrated Query (LINQ) (C#) 

Traditionally If you think about queries the main thing that comes into your mind is that queries are raw strings that can use to get the data from some dataset that are expressed as strings without checking anything like compile time or IntelliSense like traditional sql server queries.

Now using LINQ you can query data sources like

• MS SQL databases and other databases
• ADO.Net Dataset
• Collections
• XML documents,
• Various Web services etc .