LINQ : An Introduction

LINQ is an acronym for “Language
Integrated Query.” It’s been around since Visual Studio 2008 but
in the works far in advance of that; however, many companies are just
now using it for the first time. It is a programming model
developed by Microsoft to allow developers to query several types of
objects as if they were querying a SQL database. For example,
developers can now query for a textbox on a form with the ease of
querying for a row in a database table – often, with less overhead.

The syntax is similar to SQL except
that the clauses are ordered differently. For example, note the
following LINQ query:
var queryProduct =
from p in products
select p.ProductName;

Common objects queryable by LINQ are
enumerable classes, arrays, datasets, and XML documents.