Type casting means conversion of one type into another type. For Ex: public partial class InheritanceEx3 : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { B b = new B(); A A = b; Casting operation for getting parent class object Down casting B b1 = (B)A; Casting operation for getting Child class object UPcasting } } public class A { public int _x; public A(int X) { _x = X; } } public class B : A { } For learning more about C# interview question you can refer this link c# interview questions