It will shift to the next index of that ArrayList.

Please follow the given example below

ArrayList a1 = new ArrayList();
a1.Add(“abc”);
a1.Add(“aa”);
a1.Add(“baba”);

//before inserting new element
Console.WriteLine(a1[2]);

//adding new element at 2nd index
a1.Insert(2, “item”);

//after added
Console.WriteLine(a1[2]);
Console.WriteLine(a1[3]);
//“baba” is shifted at index 3 now

Console.ReadLine();