C# の配列型の参照/参照パラメーターとは何ですか?

public void swap(ref int x, ref int y) {}

static void Display(ref int[] myArr)

class TestRef {
   static void Display(ref int[] myArr) {
      if (myArr == null) {
         myArr = new int[10];
      }

      myArr[0] = 345;
      myArr[1] = 755;
      myArr[2] = 231;
   }

   static void Main() {
      int[] arr = { 98, 12, 65, 45, 90, 34, 77 };

      Display(ref arr);

      for (int i = 0; i < arr.Length; i++) {
         System.Console.Write(arr[i] + " ");
      }

      System.Console.ReadKey();
   }
}