>>>It;s just a class declaration within a class.
>>>

>>>	class TheClass
>>>	{
>>>		public void Work()
>>>		{
>>>
>>>			PrivateClass hello = new PrivateClass();
>>>
>>>			hello.DoWork(); // with parameters needed
>>>			Console.WriteLine("{0} {1}", hello.StartTime, hello.EndTime);
>>>			Console.ReadLine();
>>>
>>>		}
>>>		private class PrivateClass
>>>		{
>>>			public DateTime StartTime { get; private set; }
>>>			public DateTime EndTime { get; private set; }
>>>
>>>			public void DoWork()
>>>			{
>>>				StartTime = DateTime.Now;
>>>				EndTime = DateTime.Now;
>>>			}
>>>
>>>		}
>>>
>>>	}
>>>	
>>>

>>
>>I see, thanks a lot - this may be very useful for me.
>
>I don't think it's much of a difference. It's just a different means of accessibility to a class. What's in the class is still the same. You instantiate it the same way and use it the same way. All that changes is where the PM finds it.

I think the difference is (as I understood this code), that this class can only be used inside the main class and it's not accessible from outside.