1)for name space inclusion 2) for code clean up.

I wish to talk more about the Using Clause. You can Use Using with all the objects that Implements IDisposable Interface, SO when you get out of the Scope of 'Using' , It Disposes the Object and it should not be further Used. This is a best known practice to do so :)

• To Import a Namespace. Example Using System.Data;
• To close the connection in ADO.Net