It is very common for applications to use data in SQL databases or XML documents. Traditionally, developers had to learn a primary programming language, such as C#, and a secondary language, such as SQL or XQuery. Language-Integrated Query (LINQ) brings query capabilities into the C# language itself. Now, instead of learning a separate query language, you can use your knowledge of C#, together with some additional keywords and concepts, to query SQL databases, ADO.NET datasets, XML documents, and any .NET collection class that implements the IEnumerable interface.
- Familiar syntax for writing queries.
- Compile-time checking for syntax errors and type safety.
- Improved debugger support.
- IntelliSense support.
- Ability to work directly with XML elements instead of creating a container XML document, as required with W3C DOM.
- In-memory XML document modification that is powerful, yet simpler to use than XPath or XQuery.
- Powerful filtering, ordering, and grouping capabilities.
- Consistent model for working with data across various kinds of data sources and formats.
For Examples of Linq Go to THIS.