LINQ programming was introduced in Chapter 6. That chapter primarily focused on LINQ to Objects, which is the default provider. The next chapter introduces three additional providers: LINQ to XML, LINQ to SQL and LINQ to DataSet. These providers implement the IQueryable interface to implement their unique behavior and extend the IEnumerable<T> interface.

You can manage, query, and change an XML store using LINQ to XML. Discard the competing models (DOM, XmlTextReader, and so forth) for accessing XML. LINQ to XML provides a unified model for querying and managing XML documents and elements. LINQ to SQL is for managing and querying relational databases. LINQ to SQL also provides a straightforward method for making changes in a disconnected environment and later persisting those changes to the database. With LINQ to DataSet, you can query datasets. By the end of the next chapter, you will have a more complete view of LINQ.