Starting .NET 3.5, Microsoft has introduced LINQ to the programmer’s world. LINQ is a set of language extensions that allow you to perform queries from a higher level programming languages such as C#, VB.NET. LINQ is all about data queries. LINQ lets a user define keywords that are used to build query expressions. Then these query expressions can be used to filter, select, group, transform or sort data. Different data sources can be manipulated using the same set of query expression. For example

LINQ to SQL: access SQL Server Database without writing any data access code manually.

LINQ to XML: read XML files without using regular .NET XML classes.

LINQ to Objects: perform queries against array and in-memory data collections.

LINQ to DataSet: query in-memory DataSet.

LINQ to Entities: decouples the entity object model from the physical database by injecting a logical mapping between the two.

LINQ articles