For example,

```
  class Age
  {
    public int Year
    {
      get;
      set;
    }
    public Age(int year)
    {
      Year = year;
    }
  }

  class Person
  {
    public Age MyAge
    {
      get;
      set;
    }
    public Person(Age age)
    {
      age.Year = ( age.Year * 2 );
      MyAge = age;      
    }
  }

```

[Client]

```
Age a = new Age(10);
Person p = new Person( a );

```

When a new `Age` class is constructed the `Year` property is: 10. However, the Person class changes the Year to 20, even though there is no ref keyword...

Can someone explain why Year is not still 10?