Close multiple forms

In the Form1 code:

Form2 f2 = new Form2();
f2.Show();
Close();

The only problem with this is that if the current form is your main form (the one that opens in the Main method of Program.cs) that this will close the application. In that case, use Hide instead of Close, or Hide it first, then use ShowDialog instead of Show - try it and you will see what I mean!