This posting is dedicated to Linq for Silverlight and introduces a new element in the Project Turing series of Jesse Liberty: definitions for terms that may not be familiar.
You can use Linq for retrieving, updating, removing or adding data to and from SQL-server or any database or from any other collection such as a list<T>, an XML file, etc. An important benefit of this is that the same logic used to retrieve specified data from an in-memory collection may be applied to your data storage layer. That is, rather than using an enumerator on your list but ADO.NET on your database, you can use a Linq query against both.