When we defined our data model, the LINQ to SQL designer also created a custom Data Context class that provides the main conduit by which we'll query our database and apply updates/changes.
In the example data model we defined above this class was named "Northwind Data Context".
In Part 2 of this series I walked through how to create a LINQ to SQL class model using the LINQ to SQL designer that is built-into VS 2008.
Below is a class model created for the Northwind sample database and which I'll be using in this blog post: When we designed our data model using the LINQ to SQL data designer above we defined five data model classes: Product, Category, Customer, Order and Order Detail.
I'm not 100% sure about LINQ but i would say that the seperation is based on transaction control.You apply any number of updates, inserts or deletes.