Using message boxes, the user of the script can provide input via clicking buttons like 'yes', 'no' and 'cancel':
Count-down message box (time-out)
With input boxes, the user of the script can enter text, a number, or select an item from a list:
File dialogs can be used to quickly retrieve a filename without having to specify the name in advance.
Custom-made dialogs are the most flexible and can contain text fields, radio buttons, check-boxes etc.
For elaborate instruction material, see the chapter on creating graphical components in Getting Scripted Guide v0.3.