A pop-up box to deliver an error message or alert. Usually created with JOptionPane methods. Temporary Window for displaying information or requesting keystrokes. It requires a parent JFrame, thus in cannot be used inside an JApplet which has no JFrame. It can be modal, which means it blocks input to all other JWindow s until it is dismissed. You can place complex arrays of Component s on JDialog s, not just simple error messages. Dialog BorderLayout