What exactly does the ServiceContext do for Linq queries?

using (ServiceContext svcContext = new ServiceContext(serviceProxy))
{
 var query_where1 = from a in svcContext.AccountSet
                    where a.Name.Contains("Contoso")
                    select a;
 foreach (var a in query_where1)
 {
  System.Console.WriteLine(a.Name + " " + a.Address1_City);
 }
}

I am trying to workout what the ServiceContext actually does. The SDK did not help.
Also what does the serviceProxy do?