LINQ (Language Integrated Query)—pronounced “link”—extends .NET to provide a way to query and transform collections, relational data, and XML documents. It provides a SQL-like syntax within C# for querying data, regardless of where that data originates.
LINQ also brings a much more declarative or functional approach to programming than previously available in .NET.
Note Functional programming is one approach to creating declarative code.
In declarative programming, the logic and requirements are expressed but the execution steps are not.
LINQ and Rx are functional aspects of the C# language, in that they focus more on what you are ...