C# 기초인데 질문이요..

[나는개념인이다(ranail)]

namespace RefTypeCopy
{
    class MyClass
    {
        public int iNum;
        public MyClass(int iParam)
        {
            iNum = iParam;
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            MyClass myObj1 = new MyClass(1024);
            MyClass myObj2;
            myObj2 = myObj1;
            Console.WriteLine("myObj1={0}, myObj2={1}",
                myObj1.iNum, myObj1.iNum);
            myObj2.iNum = 2048;
            Console.WriteLine("myObj1={0}, myObj2={1}",
                myObj1.iNum, myObj2.iNum);
        }

 

여기서 myObj2.iNum = 2048; 를 써넣었는데

왜 myObj1.iNum도 2048로 변하는지 궁금합니다