It's an acronym for Language Integrated Query. Language Integrated Query (LINQ) is a Microsoft project that adds a native querying syntax reminiscent of SQL to .NET Framework programming languages, initially to the C# and Visual Basic .NET languages.

SQL cache dependency is the ability to invalidate a database cache if data in a table is changed.

LINQ defines standard query operators that allow code written in LINQ-enabled languages to filter, enumerate, and create projections of several types of collections using the same syntax. Such collections may include arrays, enumerable classes, XML, datasets from relational databases, and third party data sources. The LINQ project uses features of version 2.0 of the .NET Framework, new LINQ-related assemblies, and extensions to the C# and Visual Basic .NET languages. Microsoft has distributed a preview release of LINQ, consisting of those libraries and compilers for C# 3.0 and Visual Basic 9. Other languages, such as F# and Nemerle, have also announced preliminary support.