LINQ is a codename for a set of extensions to the .NET Framework that encompass language-integrated query, set, and transform operations. It extends C# and Visual Basic with native language syntax for queries and provides class libraries to take advantage of these capabilities.More details on LINQ: http://www.c-sharpcorner.com/1/180/linq.aspx

LINQ address the current database development model in thecontext of Object Oriented Programming Model. If we want to develop database applicationin .Net platform then there will be very simple approach like we will useADO.NET because it will work as a middleware to connect database, for businesslogic we should be good in C# or VB.NET so overall we should have goodknowledge in both database programming (SQL) and in Object Oriented Programmingbut here SQL statements become the part of C# and VB.NET code in the form ofLINQ. So we can write database code in C# or VB.NET.LINQ has a great power of querying on any source of data,data source could be the collections of objects, database or XML files. We caneasily retrieve data from any object that implements the IEnumerable interface. Microsoft divides LINQ into three areas.LINQ to Object {Queries performed against the in-memory data}LINQ to ADO.NetLINQ to SQL (formerly DLinq) {Queries performed against the relation database only Microsoft SQL Server Supported}LINQ to DataSet {Supports queries by using ADO.NET data sets and data tables}LINQ to Entities {Microsoft ORM solution} LINQ to XML (formerly XLinq) { Queries performed against the XML source} refereed from: http://www.mindstick.com/blog/8/What%20is%20LINQ

LINQ stands for language integrated query. It is a uniform programming model for querying and manipulation data with a consistent model from any data source. It can also be called as an another tool for embedding SQL queries into code. It extends powerful query capabilities to c#, vb.net languages.Its syntax:from id in source { from id in source | where condition } [orderby ordering , ordering, ....] select expr | group expr by key [into id query]

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,[1] PHP, JavaScript and ActionScript.

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,[1] PHP, JavaScript and ActionScript.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[2] or monadic parsers.[3]

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,[1] PHP, JavaScript and ActionScript.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[2] or monadic parsers.[3]

LINQ is the Feature Which is Introduced in .NET Framework 3.5. It is used to intragrate the SQL server to Visual Studio .

LINQ-Language Integrated Query.This is a .Net Framework 3.5 feature.This feature is very usefull to query on collections.