There are a handful of classes in the System.Data.Linq namespace that you will use on a regular basis when using LINQ to SQL. The following section is meant to provide a brief overview of these classes, their purposes, and where they fit in the scheme of LINQ to SQL.
An entity class on the one side of a one-to-many relationship stores its associated many entity classes in a class member of type EntitySet<T> where type T is the type of the associated entity class.
Since, in the Northwind database, the relationship between Customers and Orders is one-to-many, in the Customer class, the Orders are stored in an EntitySet<Order>.
private EntitySet<Order> _Orders;
The EntitySet<T> class is a special ...