What does question mark and dot operator ?. mean in C# 6.0?

CSharp · Console

/Program.cs

using System;
					
public class Program
{
	public static void Main()
	{
		var Model = new Model
		{
			Model2 = new Model2
			{
				Model3 = new Model3
				{
					Model4 = new Model4()
				}
			}
		};
		
		Console.WriteLine("Name is null: {0}", Model.Model2.Model3.Model4.Name == null);
		
		var name = Model.Model2?.Model3?.Model4?.Name ?? "N/A";

		Console.WriteLine(name);
	}
	
	public class Model
	{
		public Model2 Model2 { get; set; }	
	}
	public class Model2
	{
		public Model3 Model3 { get; set; }	
	}
	public class Model3
	{
		public Model4 Model4 { get; set; }	
	}
	public class Model4
	{
		public string Name { get; set; }	
	}
}