title: Method is returning List when the method return type IEnumerable.But GetType shows as List
body: <p>Though, the below question seems to be silly, but still it would help others also. I have method that return a list.And the method return type IEnumnerable.
  Method:</p>
  
  <pre><code>public class Person
      {
          public string Name { get; set; }
          public int Age { get; set; }
  
          public static IEnumerable&lt;Person&gt; GetPersons()
          {
              List&lt;Person&gt; personList = new List&lt;Person&gt;()
                                            {
                                                new Person() { Age = 10, Name = "Vijay"}
                                            };
  
             return personList;
  
          }
      }
  </code></pre>
  
  <p>Now whenever I am calling this method and checking the type.The output is </p>
  
  <pre><code>System.Collections.Generic.List
  </code></pre>
  
  <p>Since it is a List. I should be able add Items to the list. But system is throwing a compilation error.
  Below is the execution part:</p>
  
  <pre><code>public class Program
      {
          public static void Main(string[] ar)
          {
              var personList = Person.GetPersons();
              Console.WriteLine(personList.GetType()); //System.Collections.Generic.List
              personList.Add(new Person(){Age = 11, Name = "Ajay"}); // Compilation error
              Console.ReadKey();
  
          }
      }
  </code></pre>
  
  <p>So could anyone help me with the understanding. It would be great help.
  Thanks in advance.</p>