Language Integrated Query (LINQ, pronounced "link") is a Microsoft .NET Framework component that adds native data querying capabilities to .NET languages, although ports exist for Java, PHP, JavaScript and ActionScript.
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.
LINQ extends the language by the addition of query expressions, which are akin to SQL statements, and can be used to conveniently extract and process data from arrays, enumerable classes, XML documents, relational databases,
and third-party data sources. Other uses, which utilize query
expressions as a general framework for readably composing arbitrary
computations, include the construction of event handlers or monadic parsers.
LINQ also defines a set of method names (called standard query operators, or standard sequence operators), along with translation rules used by the compiler to translate fluent-style query expressions into expressions using these method names, lambda expressions and anonymous types.
Many of the concepts that LINQ has introduced were originally tested in Microsoft's Cω research project. LINQ was released as a major part of .NET Framework 3.5 on November 19, 2007.